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The Alluna RC-20 Ritchey Chrétien telescope was installed in March, 2016.
The 20-inch telescope is able to locate and track any sky object (including Earth satellites and the International Space Station) with software called TheSkyX Professional,
into which is embedded a unique T-Point model created for our site with the telescope itself.
Explanatory Notes:
Times for transient sky phenomena are given using a 24 hour clock, i.e. 20:30 hrs = 8.30 pm. Times are in Australian Eastern Standard Time (AEST), which equals Universal Time (UT) + 10 hours. Daylight saving is not observed in
Queensland. Observers in other time zones will need to make their own corrections where appropriate. With conjunctions of the Moon, planets and stars, timings indicate the closest approach. Directions (north or south) are
approximate. The Moon’s diameter is given in arcminutes ( ’ ). The Moon is usually about 30’ or half a degree across. The 'limb' of the Moon is its edge as projected against the sky background.
Rise and set times are given for the theoretical horizon, which is a flat horizon all the way round the compass, with no mountains, hills, trees or buildings to obscure
the view. Observers will have to make allowance for their own actual horizon.
Transient phenomena are provided for the current month and the next. Geocentric phenomena are calculated as if the Earth were fixed in space as the ancient Greeks believed. This viewpoint is useful, as otherwise
rising and setting times would be meaningless. In the list of geocentric events, the nearer object is given first.
When a planet is referred to as ‘stationary’, it means that its movement across the stellar background appears to have ceased, not that the planet itself has stopped. With inferior planets (those inside the Earth’s
orbit, Mercury and Venus), this is caused by the planet heading either directly towards or directly away from the Earth. With superior planets (Mars out to Pluto), this phenomenon is caused by the planet either beginning or ending its
retrograde loop due to the Earth’s overtaking it.
Apogee and perigee: Maximum and minimum distances of the Moon or artificial satellite from the Earth.
Aphelion and perihelion: Maximum and minimum distances of a planet, asteroid or comet from the Sun.
Eclipses always occur in pairs, a lunar and a solar but not necessarily in that order, two weeks apart.
All astronomical objects rise until they reach the meridian, then they begin to
set. The act of crossing or 'transitting' the meridian is called 'culmination'. The best time to observe the Moon and planets is when they are culminating. Objects closer to the South Celestial Pole than its altitude above the southern
horizon do not rise or set, but are always above the horizon, constantly circling once each sidereal day. They are called 'circumpolar'. The brightest circumpolar star from Nambour is Miaplacidus (Beta Carinae, magnitude = 1.67).
A handspan at arm's length with fingers spread covers an angle of approximately 18 - 20 degrees. Your closed fist at arm's length is 10 degrees across. The tip of your index finger at arm's
length is 1 degree across. These figures are constant for most people, whatever their age. The Southern Cross is 6 degrees high and 4 degrees wide, and Orion's Belt is 2.7 degrees long. The Sun and Moon average half-a-degree (30 arcminutes) across.
mv = visual magnitude or brightness. Magnitude 1 stars are very bright, magnitude 2 less so, and magnitude 6 stars are so faint that the unaided eye can only just detect them under good, dark conditions. Binoculars will allow
us to see down to magnitude 8, and the Observatory telescope can reach visual magnitude 17 or 22 photographically. The world's biggest telescopes have detected stars and galaxies as faint as magnitude 30. The sixteen very brightest
stars are assigned magnitudes of 0 or even -1. The brightest star, Sirius, has a magnitude of -1.44. Jupiter can reach -2.4, and Venus can be more than 6 times brighter at magnitude -4.7, bright enough to cast shadows. The Full Moon can
reach magnitude -12 and the overhead Sun is magnitude -26.5. Each magnitude step is 2.51 times brighter or fainter than the next one, i.e. a magnitude 3.0 star is 2.51 times brighter than a magnitude 4.0. Magnitude 1.0 stars are 100 times
brighter than magnitude 6.0 (5 steps each of 2.51 times, 2.51x2.51x2.51x2.51x2.51 = 2.515 =
How long does it take the Earth to complete one rotation? No, it's not 24 hours - that is the time taken for the Sun to cross the meridian on successive days. This 24 hours is a little longer than one complete rotation, as the curve in the Earth's orbit means that it needs to turn a fraction more (~1 degree of angle) in order for the Sun to cross the meridian again. It is called a 'solar day'. The stars, clusters, nebulae and galaxies are so distant that most appear to have fixed positions in the night sky on a human time-scale, and for a star to return to the same point in the sky relative to a fixed observer takes 23 hours 56 minutes 4.0916 seconds. This is the time taken for the Earth to complete exactly one rotation, and is called a 'sidereal day'.
As our clocks and lives are organised to run on solar days of 24 hours, and the stars circulate in 23 hours 56 minutes approximately, there is a four minute difference between the movement of the Sun and the movement of the stars. This causes the following phenomena:
1. The Sun slowly moves in the sky relative to the stars by four minutes of time or one degree of angle per day. Over the course of a year it moves ~4 minutes X 365 days = 24 hours, and ~1 degree X 365 = 360 degrees or a complete circle. Together, both these facts mean that after the course of a year the Sun returns to exactly the same position relative to the stars, ready for the whole process to begin again.
2. For a given clock time, say 8:00 pm, the stars on consecutive evenings are ~4 minutes or ~1 degree further on than they were the previous night. This means that the stars, as well as their nightly movement caused by the Earth's rotation, also drift further west for a given time as the weeks pass. The stars of autumn, such as Orion, are lost below the western horizon by mid-June, and new constellations, such as Sagittarius, have appeared in the east. The stars change with the seasons, and after a year, they are all back where they started, thanks to the Earth's having completed a revolution of the Sun and returned to its theoretical starting point.
We can therefore say that the star patterns we see in the sky at 11:00 pm tonight will be identical to those we see at 10:32 pm this day next week (4 minutes X 7 = 28 minutes earlier), and will be identical to those of 9:00 pm this date next month or 7:00 pm the month after. All the above also includes the Moon and planets, but their movements are made more complicated, for as well as the Four Minute Drift with the stars, they also drift at different rates against the starry background, the closest ones drifting the fastest (such as the Moon or Venus), and the most distant ones (such as Saturn or Neptune) moving the slowest.
A suggestion for successful sky-watching
Observing astronomical objects depends on whether the sky is free of clouds. Not only that, but there are other factors such as wind, presence of high-altitude jet streams, air temperature,
humidity (affecting dew formation on equipment), transparency (clarity of the air), "seeing" (the amount of air turbulence present), and air pressure. Even the finest optical telescope has its performance constrained by these factors.
Fortunately, there is an Australian website that predicts the presence and effects of these phenomena for a period up to five days ahead of the current date, which enables amateur and professional astronomers to plan their observing
sessions for the week ahead. It is called "SkippySky". The writer has found its predictions to be quite reliable, and recommends the website as a practical resource. The website is at
http://skippysky.com.au and the detailed Australian data are at
http://skippysky.com.au/Australia/ .
Solar System
The Sun begins the month in the zodiacal constellation of Aquarius, the Water Bearer. It crosses into Pisces, the Fishes on March 12. Note: the Zodiacal constellations used in astrology have significant differences
with the familiar astronomical constellations both in size and the timing of the passage through them of the Sun, Moon and planets.
The animation loop below shows the appearance of the Moon over one month. The changing phases are obvious, as is the changing size as the Moon comes closer to Earth at perigee, and moves away from the Earth at apogee. The wobble due to
libration is the other feature to note, making the Moon appear to sway from side to side and nod up and down. (Credit: Wikipedia)
.gif)
Eclipses this month
Partial Lunar Eclipse, 14 March 2025:
The next lunar eclipse visible from Australia will occur on this evening, but
people living in south-east Queensland will only see a partial phase, as the
total phase will begin before the Moon has risen above our horizon. The
following timings are for the Sunshine Coast:
The penumbral phase of the eclipse will start at 1:56 pm. The umbral phase will begin at 3:09 pm. Totality will begin at 4:26 pm and end at 5:31 pm. Moonrise will occur at
6:07 pm, when about half of the Moon will be eclipsed. This partial umbral phase will end at 6:48 pm, after which no eclipse will be noticeable. The faint penumbral phase will end at 8 pm, when the Full Moon will appear
slightly brighter than normal.
No part of this eclipse of the Sun will be visible from anywhere in Australia, but it will be visible from Greenland,
Labrador, Iceland, United Kingdom, Europe, Scandinavia and Northern Russia. As there is no place experiencing a total eclipse, there is no eclipse path.
First Quarter:
March 7
Last Quarter:
March 22 21:31 hrs
diameter = 30.3'
First Quarter:
April
Last Quarter:
April 21
Moon at 8 days after New, as on March 8.
A professional version of this freeware with excellent pictures from the Lunar Reconnaissance Orbiter and the Chang orbiter (giving a resolution of 50 metres on the Moon's surface) and many other useful features is available on a DVD from the same website for 20 Euros (about AU $ 33) plus postage.
Lunar Feature for this Month:
Each month we describe a lunar crater, cluster of craters, valley, mountain range or other object, chosen at random, but one with interesting attributes. A recent photograph from our Alluna RC20 telescope will illustrate the object. As all large lunar objects are named, the origin of the name will be given if it is important. This month's feature is the area at the extreme north end of the Oceanus Procellarum (Ocean of Storms). It extends west to longitude 80º west and south to latitude 46º north. It includes an ancient walled plain called Xenophanes and a much more recent crater called Markov. This area lies to the south-west of the area described last month.
The crater plains Cleostratus and Oenopides seen near the left margin of the second image featured last month, now appear at the right margin of this image. Fresh moonscapes around the crater Markov (41 kilometres) and the walled plain Repsold (108 kilometres) have now come into view. The large flat areas in this and subsequent images are part of the extensive lava plain known as the Oceanus Procellarum (Ocean of Storms), which has an area of 2.1 million square kilometres. The complete wall of the large crater plain Xenophanes (121 kilometres) is visible, but its floor remains in shadow except for the illuminated summits of a mountainous spine running north-east to south-west and an illuminated summit on the northern wall of a 35 kilometre crater-plain on the west half of Xenophanes' floor (seen below). The upper left corner of this image shows a black void which is the dark interior of the walled plain Volta (113 kilometres). The outside of the curved southern wall of Volta is seen clearly.
The same area of the Moon, photographed at 8:12 pm on 23 May 2024.
In this image, taken 22 hours later, the whole walled plain of
Volta has been filled with sunlight, revealing a mountain and two craters on the
floor, and another crater, Volta D (20 kilometres), which has impacted on the south-western wall. The far (northern) wall of Volta has been impacted by the secondary crater
Regnault (48 kilometres),
which also has been revealed by the rising Sun. The left side of this image shows part of the complex floor of the crater-plain
Repsold (108 kilometres) which is shown in full
in the next four images.
In this image, the walled plain Volta was still in shadow, as was nearby Galvani (80 kilometres). The recent cone crater Dechen (12 kilometres) is isolated in the Oceanus Procellarum. Repsold has a squarish shape, each diagonal approximating 108 kilometres. Its flat floor has numerous craterlets, and is crossed by several V-shaped rilles and some grabens (rift valleys), but these can only be observed a day later if the libration allows. Repsold's north-west corner has been struck by a large impactor, creating a secondary crater called Repsold G (44 kilometres). Near the left margin is a small cone-shaped crater called Repsold T (13 kilometres). It is indicated on this image and three others by the letter T, and can be used to link this image with others in this Group and the next.
Much the same area of the Moon, photographed at 8:16 pm on 23 May 2024.
The rising Sun which has illuminated the interiors of the craters Volta and Regnault has also revealed details in the interiors of Galvani, Gerard Q Inner and Outer, Repsold and Repsold G. The previously unseen craters Stokes (51 kilometres), Langley (60 kilometres), McLaughlin (79 kilometres) and McLaughlin B (43 kilometres) have also become visible.
Galvani
Luigi Galvani (1737-1798) was an Italian physician, physicist, biologist and philosopher who studied what was then called ‘medical’ or ‘animal electricity’. This field emerged in the middle of the 18th century, following electrical researches and the discovery of the effects of electricity on the human body by various European scientists in the.1770s.
In 1780, using a
frog, he discovered that the muscles of dead frogs' legs contracted or twitched
when struck by an electrical spark. This was an early study of
bioelectricity, following experiments
by John
Walsh and Hugh
Williamson. He concluded that every animal cell has a
cell potential, and that biological
electricity was distributed around a body by ‘animal electric fluid’. This fluid
existed only in living creatures, so it was believed for a time that electricity
was only to be found in living beings.
Volta Alessandro Giuseppe Antonio Anastasio Volta
Volta drew
admiration from Napoleon
Bonaparte for his invention, and was invited to the
Institute of France to demonstrate his invention to the members of the institute. Throughout his life, Volta enjoyed a certain amount of closeness with the emperor who conferred upon him numerous
honours. Volta held the chair of experimental physics at the University
of Pavia for nearly 40 years and was widely idolised by his students.
The SI unit of electric potential, e.g. “240 volts” is named the ‘volt’ in
his honour. Galvani did not agree totally with Volta’s discoveries, but both men respected
each other and corresponded regularly. When Volta built the first electric circuits using battery power, he gave a nod to his rival by coining the term “Galvanism” for a direct current of electricity produced by chemical reaction.
The area south-west of the North Pole from Oenopides to McLaughlin is located inside the rectangle.
Click
here
for the
It should be remembered that close approaches of Moon, planets and stars are only perspective effects as seen from the Earth - that is why they are called 'geocentric or Earth-centred phenomena'. The Moon, planets and stars do not
really approach and dance around each other as it appears to us from the vantage point of our speeding planet.
March 1: Moon 1.4º of Saturn at 3:37 hrs
March 1: Moon occults Mercury between 13:59 and 14:55 hrs
March 1: Moon 2.2º north of Neptune at 19:13 hrs
March 2: Venus at eastern stationary point at 10:03 hrs ( diameter = 49.5" )
March 2: Moon 5.3º south of Venus at 12:51 hrs
March 3: Mercury 1.8º north of Neptune at 2:46 hrs
March 3: Jupiter at eastern quadrature at 4:12 hrs ( diameter = 39.3" )
March 3: Jupiter 1.1º south of the star 94 Tau Tauri (mv = 4.24) at 23:41 hrs
March 4: Mercury at perihelion at 23:35 hrs (diameter = 6.6" )
March 5: Moon 4.8º north of Uranus at 10:49 hrs
March 6: Moon 1º north of the star Alcyone (Eta Tauri, mv = 2.85) at 00:41 hrs
March 6: Moon 6.2º north of Jupiter at 21:34 hrs
March 7: Moon occults the star Elnath (Beta Tauri, mv = 1.65) between 12:09 and at 12:37 hrs
March 8: Mercury at Greatest Elongation East (18º 09') at 11:27 hrs ( diameter = 7.3" )
March 9: Moon 1.7º north of Mars at 10:05 hrs
March 9: Moon 1.2º south of the star Pollux (Beta Geminorum, mv = 1.1) at 20:49 hrs
March 12: Saturn in conjunction with the Sun at 20:23 hrs ( diameter = 15.6" )
March 13: Uranus 2.4º south of the star 63 Arietis (mv = 5.28) at 21:55 hrs
March 15: Mercury at eastern stationary point at 16:50 hrs ( diameter = 9.1" )
March 17: Limb of Moon 6 arcminutes south of the star Spica (Alpha Virginis, mv = 0.95) at 7:33 hrs
March 19: Neptune 1.7º north of the star 29 Piscium (mv = 5.11) at 8:11 hrs
March 20: Neptune in conjunction with the Sun at 9:23 hrs ( diameter = 2.2" )
March 20: Moon 1.2º north of the star Pi Scorpii (mv = 2.82) at 13:53 hrs
March 20: Limb of Moon 6 arcminutes south of the star Alniyat (Sigma Scorpii, mv = 2.9) at 21:10 hrs
March 21: Limb of Moon 1 arcminute south of the star Antares (Alpha Scorpii, mv = 0.88) at 01:17 hrs
March 21: Limb of Moon 44 arcminutes north of the star 23 Tau Scorpii (mv = 2.82) at 6:39 hrs
March 22: Moon 2.4º north of the star Alnasl (Gamma Sagittarii, mv = 2.98) at 19:58 hrs
March 23: Moon 1.2º north of the star Kaus Media (Delta Sagittarii, mv = 2.72) at 1:25 hrs
March 23: Venus in inferior conjunction with the Sun at 11:23 hrs ( diameter = 59.4" )
March 23: Limb of Moon 38 arcminutes south of the star Nunki (Sigma Sagittarii, mv = 2.02) at 17:54 hrs
March 25: Mercury in inferior conjunction at 5:44 hrs ( diameter = 11.1" )
March 26: Limb of Moon 36 arcminutes south-south-east of Pluto at 7:21 hrs
March 26: Limb of Moon 10 arcminutes north of the star Deneb Algedi (Delta Capricorni,(mv = 2.85) at 19:31 hrs
March 28: Moon 2.2º north of Saturn at 21:31 hrs
March 29: Moon 7.6º south of Venus at 3:39 hrs
March 29: Moon 1.5º north of Neptune at 4:56 hrs
March 29: Moon 2.1º south of Mercury at 6:18 hrs
April 1: Moon 5º north of Uranus at 23:05 hrs
April 2: Limb of Moon arcminutes north of the star Alcyone (Eta Tauri, mv = 2.85) at 5:57 hrs
April 3: Moon 5.6º north of Jupiter at 8:21 hrs
April 3: Limb of Moon 5 arcminutes north of the star Elnath (Beta Tauri, mv = 1.65) at 22:12 hrs
April 6: Moon 2.1º north of Mars at 6:10 hrs
April 7: Mercury at western stationary point at 20:53 hrs ( diameter = 10.2" )
April 8: Jupiter 1º north of the star 102 Iota Tauri (mv = 4.62) at 12:14 hrs
April 13: Venus at western stationary point at 10:38 hrs ( diameter = 48.7" )
April 13: Moon occults the star Spica (Alpha Virginis, mv = 0.95) between at 12:13 and 12:26 hrs (may be a grazing occultation at some locations)
April 16: Moon 1.4º north of the star Pi Scorpii (mv = 2.82) at 18:04 hrs
April 17: Limb of Moon 35 arcminutes south of the star Alniyat (Sigma Scorpii, mv = 2.9) at 6:18 hrs
April 17: Moon occults the star Antares (Alpha Scorpii, mv = 0.88) between 10:05 hrs and 10:54 hrs
April 17: Mars at aphelion at 9:19 hrs ( diameter = 7.3" )
April 17: Mercury 42 arcminutes south of Neptune at 14:58 hrs
April 17: Moon 1.7º north of the star 23 Tau Scorpii (mv = 2.82) at 13:02 hrs
April 17: Mercury at aphelion at 23:15 hrs ( diameter = 8.5" )
April 19: Moon 1.8º north of the star Alnasl (Gamma Sagittarii, mv = 2.98) at 2:28 hrs
April 19: Moon 1.8º north of the star Kaus Media (Delta Sagittarii, mv = 2.72) at 11:15 hrs
April 19: Moon 1.3º south of the star Nunki (Sigma Sagittarii, mv = 2.02) at 23:14 hrs
April 21: Mars at eastern quadrature at 10:58 hrs ( diameter = 7.0" )
April 21: Moon occults Pluto at 16:21 hrs
April 22: Mercury at Greatest Elongation West (27º 17') at 00:58 hrs ( diameter = 7.9" )
April 23: Limb of Moon grazes the star Deneb Algedi (Delta Capricorni,(mv = 2.85) at 2:58 hrs
April 24: Pluto at western quadrature at 2:47 hrs ( diameter = 0.1" )
April 25: Moon 2.8º north of Saturn at 14:01 hrs
April 25: Moon 1.2º south of Venus at 14:08 hrs
April 25: Venus 4.1º north of Saturn at 15:07 hrs
April 25: Moon 2.2º north of Neptune at 19:29 hrs
April 26: Moon 4º north of Mercury at 7:12 hrs
April 29: Jupiter 46 arcminutes north of the star 109 Tauri (mv = 4.96) at 3:20 hrs
April 29: Moon 5.1º north of Uranus at 9:32 hrs
April 29: Moon 1.2º north of the star Alcyone (Eta Tauri, mv = 2.85) at 18:20 hrs
OK
Mercury:
Venus:
(The coloured fringes to the second, fourth and fifth images below are due to refractive effects in our own atmosphere, and are not intrinsic to Venus itself. The planet was closer to the horizon when these images were taken than it was for the first and third photographs, which were taken when Venus was at its greatest elongation from the Sun.)
mid-January 2025
late February 2025
mid-April 2025
early June 2025
January 2026
Click here for a photographic animation showing the Venusian phases. Venus is always far brighter than anything else in the sky except for the Sun and Moon. For most of 2023, Venus appeared as an 'Evening Star' in the western twilight sky, but in August 2023 it moved to the pre-dawn eastern sky to be a 'Morning Star'. It returned to the western evening sky as an 'Evening Star' last June. In the second half of this month it is too close to the Sun for safe observations. It will reappear in the pre-dawn eastern sky as a 'Morning Star' in April.
Because Venus is visible as the 'Evening Star' and as the 'Morning Star', astronomers of ancient times believed that it was two different objects. They called it Hesperus when it appeared in the evening sky and Phosphorus when it was seen before dawn. They also realised that these objects moved with respect to the so-called 'fixed stars' and so were not really stars themselves, but planets (from the Greek word for 'wanderers'). When it was finally realised that the two objects were one and the same, the two names were dropped and the Greeks applied a new name Aphrodite (Goddess of Love) to the planet, to counter Ares (God of War). We use the Roman versions of these names, Venus and Mars, for these two planets.
Venus at 6.55 pm on September 7, 2018. The phase is 36 % and the angular diameter is 32 arcseconds.
Mars:
At the beginning of March, the red planet is cruising in a westerly direction in the eastern part of the constellation Gemini. As twilight fades (7 pm), it can be found about two handspans above the north-north-eastern horizon. On March 1, Mars will form an isosceles triangle with the two stars marking the heads of the Gemini Twins, Pollux and Castor. The Earth overtook Mars on January 16, and we are rapidly leaving it behind. It is becoming smaller and fainter with each passing week. On March 1 its magnitude will be -0.3 and its angular diameter will be 10.8 arcseconds. By April 1 these will have fallen to magnitude 0.37 and 8.2 arcseconds. Mars completed its retrograde loop on February 24, and is now heading eastwards through the constellations once more. It will enter Cancer on April 13 and will pass through outlying stars in the Praesepe star cluster on May 5. Mars will cross into Leo on May 26, when it will be quite small and faint. The waxing gibbous Moon will be in the vicinity of Mars on March 8 and 9.
In this image, the south polar cap of Mars is easily seen. Above it is a dark triangular area known as Syrtis Major. Dark Sinus Sabaeus runs off to the left, just south of the equator. Between the south polar cap and the equator is a large desert called Hellas. The desert to upper left is known as Aeria, and that to the north-east of Syrtis Major is called Isidis Regio. Photograph taken in 1971.
Mars photographed from Starfield Observatory, Nambour on June 29 and July 9, 2016, showing two different sides of the planet. The north polar cap is prominent.
Brilliant Mars at left, shining at magnitude 0.9, passes in front of the dark molecular clouds in Sagittarius on October 15, 2014. At the top margin is the white fourth magnitude star 44 Ophiuchi. Its type is A3 IV:m. Below it and to the left is another star, less bright and orange in colour. This is the sixth magnitude star SAO 185374, and its type is K0 III. To the right (north) of this star is a dark molecular cloud named B74. A line of more dark clouds wends its way down through the image to a small, extremely dense cloud, B68, just right of centre at the bottom margin. In the lower right-hand corner is a long dark cloud shaped like a figure 5. This is the Snake Nebula, B72. Above the Snake is a larger cloud, B77. These dark clouds were discovered by Edward Emerson Barnard at Mount Wilson in 1905. He catalogued 370 of them, hence the initial 'B'. The bright centre of our Galaxy is behind these dark clouds, and is hidden from view. If the clouds were not there, the galactic centre would be so bright that it would turn night into day.
Mars near opposition, July 24, 2018
Mars, called the red planet but usually coloured orange, in mid-2018 took on a yellowish tint and brightened by 0.4 magnitude, making it twice as bright as previous predictions for the July 27 opposition. These phenomena were caused by a great dust storm which completely encircled the planet, obscuring the surface features so that they were only seen faintly through the thick curtain of dust. Although planetary photographers were mostly disappointed, many observers were interested to see that the yellow colour and increased brightness meant that a weather event on a distant planet could actually be detected with the unaided eye - a very unusual thing in itself.
The three pictures above were taken on the evening of July 24, at 9:05, 9:51 and 11:34 pm. Although the fine details that are usually seen on Mars were hidden by the dust storm, some of the larger features can
be discerned, revealing how much Mars rotates in two and a half hours. Mars' sidereal rotation period (the time taken for one complete rotation or 'Martian day') is 24 hours 37 minutes 22 seconds - a little longer than an
Earth day. The dust storm began in the Hellas Desert on May 31, and after two months it still enshrouded the planet. In September it began to clear, but by then the close approach had passed.
Central meridian: 295º.
The two pictures immediately above were taken on the evening of September 7, at 6:25 and 8:06 pm. The dust storm was finally abating, and some of the surface features were becoming visible once again. This pair of images also demonstrates the rotation of Mars in 1 hour 41 minutes (equal to 24.6 degrees of longitude), but this time the view is of the opposite side of the planet to the set of three above. As we were now leaving Mars behind, the images are appreciably smaller (the angular diameter of the red planet had fallen to 20 arcseconds). Well past opposition, Mars on September 7 exhibited a phase effect of 92.65 %.
Central meridian: 180º.
Jupiter: Jupiter passed though opposition on December 8 and will pass through eastern quadrature (due north at sunset) on March 3. It is currently in the constellation Taurus. The First Quarter Moon will be below Jupiter, close to the north-north-western horizon at 7 pm on March 6. Jupiter will be in conjunction with the Sun on June 25.
Jupiter as
photographed from Nambour on the evening of April 25, 2017. The images were taken, from left to right, at 9:10, 9:23, 9:49, 10:06 and 10:37 pm. The rapid rotation of this giant planet in a little under 10 hours is clearly seen. In the
southern hemisphere, the Great Red Spot (bigger than the Earth) is prominent, sitting within a 'bay' in the South Tropical Belt. South of it is one of the numerous White Spots. All of these are features in the cloud tops of Jupiter's atmosphere.
Jupiter at opposition, May 9, 2018
Jupiter as it appeared at 7:29 pm on July 2, 2017. The Great Red Spot was in a similar position near Jupiter's eastern limb (edge) as in the fourth picture in the series above. It will be seen that in the past two months the position of
the Spot had drifted when compared with the festoons in the Equatorial Belt, so must rotate around the planet at a slower rate. In fact, the Belt enclosing the Great Red Spot rotates around the planet in 9 hours 55 minutes, and the
Equatorial Belt takes five minutes less. This high rate of rotation has made the planet quite oblate. The prominent 'bay' around the Red Spot in the five earlier images appeared to be disappearing, and a darker streak along the northern edge
of the South Tropical Belt was moving south. In June this year the Spot began to shrink in size, losing about 20% of its diameter. Two new white spots have developed in the South Temperate Belt, west of the Red Spot. The five upper
images were taken near opposition, when the Sun was directly behind the Earth and illuminating all of Jupiter's disc evenly. The July 2 image was taken just four days before Eastern Quadrature, when the angle from the Sun to Jupiter and
back to the Earth was at its maximum size. This angle means that we see a tiny amount of Jupiter's dark side, the shadow being visible around the limb of the planet on the left-hand side, whereas the right-hand limb is clear and sharp.
Three of Jupiter's Galilean satellites are visible, Ganymede to the left and Europa to the right. The satellite Io can be detected in a transit of Jupiter, sitting in front of the North Tropical Belt, just to the left of its centre.
Jupiter reached opposition on May 9, 2018 at 10:21 hrs, and the above photographs were taken that evening, some ten to twelve hours later. The first image above was taken at 9:03 pm, when the Great Red Spot was approaching Jupiter's central meridian and the satellite Europa was preparing to transit Jupiter's disc. Europa's transit began at 9:22 pm, one minute after its shadow had touched Jupiter's cloud tops. The second photograph was taken three minutes later at 9:25 pm, with the Great Red Spot very close to Jupiter's central meridian.
The third photograph was taken at 10:20 pm, when Europa was approaching Jupiter's central meridian. Its dark shadow is behind it, slightly below, on the clouds of the North Temperate Belt. The shadow is partially eclipsed by Europa itself. The fourth photograph at 10:34 pm shows Europa and its shadow well past the central meridian. Europa is the smallest of the Galilean satellites, and has a diameter of 3120 kilometres. It is ice-covered, which accounts for its brightness and whitish colour. Jupiter's elevation above the horizon for the four photographs in order was 50º, 55º, 66º and 71º. As the evening progressed, the air temperature dropped a little and the planet gained altitude. The 'seeing' improved slightly, from Antoniadi IV to Antoniadi III. At the time of the photographs, Europa's angular diameter was 1.57 arcseconds. Part of the final photograph is enlarged below.
Jupiter at 11:34 pm on May 18, nine days later. Changes in the rotating cloud patterns are apparent, as some cloud bands rotate faster than others and
interact. Compare with the first photograph in the line of four taken on May 9. The Great Red Spot is ploughing a furrow through the clouds of the South Tropical Belt, and is pushing up a turbulent bow wave.
Jupiter at opposition, June 11, 2019
Jupiter reached opposition on June 11, 2019 at 01:20 hrs, and the above photographs were taken that evening, some twenty to twenty-two hours later. The first image above was taken at 10:01 pm, when the Great Red Spot was leaving Jupiter's central meridian and the satellite Europa was preparing to transit Jupiter's disc. Europa's transit began at 10:11 pm, and its shadow touched Jupiter's cloud tops almost simultaneously. Europa was fully in transit by 10:15 pm. The second photograph was taken two minutes later at 10:17 pm, with the Great Red Spot heading towards Jupiter's western limb.
The third photograph was taken at 10:41 pm, when Europa was about a fifth of its way across Jupiter. Its dark shadow is trailing it, slightly below, on the clouds of the North Temperate Belt. The shadow is partially eclipsed by Europa itself. The fourth photograph at 10:54 pm shows Europa and its shadow about a quarter of the way across. This image is enlarged below. The fifth photograph shows Europa on Jupiter's central meridian at 11:24 pm, with the Great Red Spot on Jupiter's limb. The sixth photograph taken at 11:45 pm shows Europa about two-thirds of the way through its transit, and the Great Red Spot almost out of sight. In this image, the satellite Callisto may be seen to the lower right of its parent planet. Jupiter's elevation above the horizon for the six photographs in order was 66º, 70º, 75º, 78º, 84º and 86º. As the evening progressed, the 'seeing' proved quite variable.
There have been numerous alterations to Jupiter's belts and spots over the thirteen months since the 2018 opposition. In particular, there have been major disturbances affecting the Great Red Spot, which appears to be slowly changing in size or "unravelling". It was very fortuitous that, during the evenings of the days when the 2018 and 2019 oppositions occurred, there was a transit of one of the satellites as well as the appearance of the Great Red Spot. It was also interesting in that the same satellite, Europa, was involved both times.
Jupiter's moon Europa has an icy crust with very high reflectivity, which accounts for its brightness in the images above. On the other hand, the largest moon Ganymede (seen below) has a surface which is composed of two types of terrain: very old, highly cratered dark regions, and somewhat younger (but still ancient) lighter regions marked with an extensive array of grooves and ridges. Although there is much ice covering the surface, the dark areas contain clays and organic materials and cover about one third of the moon. Beneath the surface of Ganymede is believed to be a saltwater ocean with two separate layers.
Jupiter is seen here on 17 November 2022 at 8:39 pm. To its far right is its largest satellite, Ganymede. This "moon" is smaller than the Earth but is bigger than Earth's Moon. Its diameter is 5268 kilometres, but at Jupiter's distance its angular diameter is only 1.67 arcseconds. Despite its small size, Ganymede is the biggest moon in the Solar System. Jupiter is approaching eastern quadrature, which means that Ganymede's shadow is not behind it as in the shadows of Europa in the two sequences taken at opposition. In the instance above as seen from Earth (which is presently at a large angle from a line joining the Sun to Ganymede), the circular shadow of Ganymede is striking the southern hemisphere cloud tops of Jupiter itself. The shadow is slightly distorted as it strikes the spherical globe of Jupiter. If there were any inhabitants of Jupiter flying across the cloud bands above, and passing through the black shadow, they would experience an eclipse of the distant Sun by the moon Ganymede.
Above is an 8X enlargement of Ganymede, showing markings on its rugged, icy surface. The dark area in its northern hemisphere is called Galileo Regio.
Saturn:
The ringed planet is located in the constellation of Aquarius, and will remain there until it crosses into Pisces on April 19. Saturn will be in conjunction with the Sun on March 12, so is not available for viewing this month. It will become observable in the eastern pre-dawn sky towards the end of April. This year, the angle between the plane of Saturn's Rings and the plane of the Earth's orbit will remain small so that the Rings look almost edge-on (see below). Simultaneously, the various moons of Saturn will line up as in the second image below.
Left: Saturn showing the Rings when edge-on. Right: Over-exposed Saturn surrounded by its satellites Rhea, Enceladus, Dione, Tethys and Titan - February 23/24, 2009.
Saturn with its Rings wide open on July 2, 2017. The shadow of its globe can just be seen on the far side of the Ring system. There are three main concentric rings: Ring A is the outermost, and is separated from the
brighter Ring B by a dark gap known as the Cassini Division, which is 4800 kilometres wide, enough to drop Australia through. Ring A also has a gap inside it, but it is much thinner. Called the 'Encke Gap', it is only 325 kilometres
wide and can be seen in the image above. The innermost parts of Ring B are not as bright as its outermost parts. Inside Ring B is the faint Ring C, almost invisible but noticeable where it passes in front of the bright planet as a
dusky band. Spacecraft visiting Saturn have shown that there are at least four more Rings, too faint and tenuous to be observable from Earth, and some Ringlets. Some of these extend from the inner edge of Ring C to Saturn's
cloudtops. The Rings are not solid, but are made up of countless small particles, 99.9% water ice with some rocky material, all orbiting Saturn at different distances and speeds. The bulk of the particles range in size from
dust grains to car-sized chunks. At bottom centre, the southern hemisphere of the planet can be seen showing through the gap of the Cassini Division. The ring system extends from 7000 to 80 000 kilometres above Saturn's equator, but its
thickness varies from only 10 metres to 1 kilometre. The globe of Saturn has a diameter at its equator of 120 536 kilometres. Being made up of 96% hydrogen and 3% helium, it is a gas giant, although it has a small, rocky core. There are
numerous cloud bands visible.
The photograph above was taken at 8:17 pm on November 03, 2022, when Saturn was again near eastern quadrature. The shadow of the planet once again falls across the far side of the rings, but in the intervening four years the angle of the
rings as seen from Earth has been greatly reduced. The shadow of Ring B across the globe of Saturn is much darker from this angle. The photograph above was taken at 8:33 pm on October 29, 2024, 51 days after opposition. The shadow of the planet once more falls across the far side of the rings, but in the intervening 11 months the angle of the rings as seen from
Earth has lessened considerably. The ring system will be difficult to observe during 2025. The light-coloured equatorial zone on Saturn is prominent, and is crossed by the black shadow of the rings on the planet.
This photograph was taken at 8:45 pm on November 4, 2024, 57 days after opposition. Although the seeing was only 3 on the Antoniadi Scale, this image was secured as it shows Saturn's largest Moon, Titan, in the same field of view as its parent
planet. Such a picture is only possible when the Rings are close to edge-on. Titan has a diameter of 5150 kilometres, and is the second largest moon in the Solar System (Jupiter's Ganymede is the largest, and our Moon is the third largest). Titan has an
atmosphere of nitrogen, methane and hydrogen, and has lakes and seas of liquid methane.
Uranus:
Neptune: Neptune, photographed from Nambour on October 31, 2008
The photograph above was taken at 7:41 pm on December 07, 2023, 14 days after eastern quadrature. The shadow of the planet once more falls across the far side of the rings, but in the intervening 13 months the angle of the rings as seen
from Earth has lessened considerably. The light-coloured equatorial zone on Saturn shows through the gap known as the Cassini Division.
The change in aspect of Saturn's rings is caused by the plane of the ring system being aligned with Saturn's equator, which is itself tilted at an angle of 26.7
degrees to Saturn's orbit. As the Earth's orbit around the Sun is in much the same plane as Saturn's, and the rings are always tilted in the same direction in space, as we both orbit the Sun, observers on Earth see the configuration of the
rings change from wide open (top large picture) to half-open (bottom large picture) and finally to edge on (small picture above). This cycle is due to Saturn taking 29.457 years to complete an orbit of the Sun, so the complete
cycle from "edge-on (2009) → view of Northern hemisphere, rings half-open (2013) → wide-open (2017) → half-open (2022) → edge-on (2025) →
view of Southern hemisphere, rings half-open (2029) → wide-open (2032) → half-open (2036) → edge-on (2039)"
Pluto:
The erstwhile ninth and most distant planet passed through conjunction with the Sun on January 21, and is now in the pre-dawn eastern sky. The best time to
observe Pluto is in our winter months when it can be found near the zenith.
Pluto's angular diameter is 0.13 arcseconds, less than one twentieth that of Neptune. Located in Capricornus, it is
close to the border with Sagittarius. It is a 14.1 magnitude object, very small and faint. A telescope with an aperture of 25 cm is capable of locating Pluto when the seeing conditions are right. The waning crescent Moon will be close to Pluto on
the morning of March 25.
The movement of the dwarf planet Pluto in two days, between 13 and 15 September, 2008. Pluto is the one object that has moved.
Width of field: 200 arcseconds
This is a stack of four images, showing the movement of Pluto over the period October 22 to 25, 2014. Pluto's image for each date appears as a star-like point at the upper right corner of the
numerals. The four are equidistant points on an almost-straight line. Four eleventh magnitude field stars are identified.
A
is GSC 6292:20, mv
= 11.6.
B
is GSC 6288:1587, mv
= 11.9.
C
is GSC 6292:171, mv
= 11.2.
D
is GSC 6292:36, mv
= 11.5. (GSC = Guide Star Catalogue).
The position of Pluto on October 24 (centre of image) was at Right Ascension = 18 hours 48 minutes 13 seconds, Declination = -20º 39' 11". The planet moved 2' 51" with respect to the stellar background
during the three days between the first and last images, or 57 arcseconds per day, or 1 arcsecond every 25¼ minutes.
Planetary
Alignments:
During March, the giant planet Jupiter will move away from the clusters in Taurus, also heading towards Gemini, but it won't reach that constellation until June 12. The waxing gibbous Moon will pass by the Pleiades on
March 5 and April 1 and 2. Here are the positions of the planets above the horizon in mid-March at 7 pm:
Jupiter is 36 degrees above the north-north-western horizon and will have set by 11 pm. The waxing crescent Moon will pass by Uranus, the Pleiades, the Hyades and Jupiter on March 5-6. It will pass by Mars on March 8-9. Mars is 34 degrees above the
north-north-eastern horizon (Jupiter is much brighter than Mars). In the first week of March, Mars will form the apex of an isosceles triamgle, with the Twin stars Castor and Pollux forming the narrower base. During the month, this triangle will change
into a right-angled triangle as Mars moves eastwards through Gemini.
The movements of planets including their alignments and close-up images can be watched using the freeware Meteor Showers:
Lyrids
April 23
Waning crescent Moon, 37% sunlit ZHR =
15 Pi Puppids
April 24
Waning crescent Moon, 25% sunlit ZHR = 10
On March 1 there will be a fine grouping of Mars, Jupiter and Uranus in the northern sky
after 8 pm. It will be quite spectacular, as the star clusters the Pleiades (Seven Sisters) and the Hyades will be nearby, as well as the bright stars Aldebaran, Betelgeuse and Capella. Not far away will be the
bright stars Sirius, Rigel, Betelgeuse and Procyon, and the Twins Pollux and Castor. Mars has been moving slowly
eastwards during February, cruising into Cancer and then Gemini as it performs its "retrograde
loop". Mars had its closest approach to Earth on January 16, when it came to "opposition". On that date, Mars appeared as its biggest and brightest. From now on, Mars will become smaller and fainter as the Earth leaves it behind.
No meteor showers in March.
Radiant: Near the star
Vega.
Associated with Comet Thatcher.
Radiant: Between the False Cross and the tail of Canis Major
Use this Fluxtimator to calculate the number of meteors predicted per hour for any meteor swarm on any date, for any place in the world.
ZHR = zenithal hourly rate (number of meteors expected to be observed at the zenith in one hour). The maximum phase of meteor showers usually occurs between 3 am and sunrise. The reason most meteors are observed in the pre-dawn hours is because at that time we are on the front of the Earth as it rushes through space at 107 000 km per hour (30 km per second). We are meeting the meteors head-on, and the speed at which they enter our atmosphere is the sum of their own speed plus ours. In the evenings, we are on the rear side of the Earth, and many meteors we see at that time are actually having to catch us up. This means that the speed at which they enter our atmosphere is less than in the morning hours, and they burn up less brilliantly.
Although most meteors are found in swarms associated with debris from comets, there are numerous 'loners', meteors travelling on solitary
paths through space. When these enter our atmosphere, unannounced and at any time, they are known as 'sporadics'. On an average clear and dark evening, an
observer can expect to see about ten meteors per hour. They burn up to ash in their passage through our atmosphere. The ash slowly settles to the ground as
meteoric dust. The Earth gains about 80 tonnes of such dust every day, so a percentage of the soil we walk on is actually interplanetary in origin. If a
meteor survives its passage through the air and reaches the ground, it is called a 'meteorite'. In the past, large meteorites (possibly comet nuclei or small asteroids) collided with the Earth and produced huge craters which still exist
today. These craters are called 'astroblemes'. Two famous ones in Australia are Wolfe Creek Crater and Gosse's Bluff. The Moon and Mercury are covered with such
astroblemes, and craters are also found on Venus, Mars, planetary satellites, minor planets, asteroids and even comets.
Comets:
Comet C/2024 G3 (ATLAS) At long last, observers in the Southern Hemisphere are favoured with a comet in their western twilight skies this month,
month, but unfortunately it has rapidly faded to magnitude 5. Look for the star
Fomalhaut. The comet is between that star and the constellation Grus, and is
heading towards the star Ankaa. Your ability to see the comet
with your naked eye will depend on your eyesight and where you live. A pair of binoculars or a spotting scope will be useful. Find a location with a good view down to the horizon, preferably away from buildings, hills and city lights. In
early February the comet was close to the horizon, but each evening it appeared higher up and slightly fainter, as it is travelling away from the Sun and us.
By February 20 it had faded to magnitude 7.
Comet C.2024 G3 (ATLAS) gets its name from how it was discovered. The "2024 G3" shows that it was the third comet discovered last year, while the facility that found it is called the "Asteroid Terrestrial-impact Last Alert System" or "ATLAS". It's hard to predict how a comet will develop in advance. Originally, some experts thought that C/2024 G3 would break apart when it reached the point in its orbit where it is at its closest to the Sun, or 'perihelion". The latest information hints that Comet C/2024 G3 may be a periodic comet, i.e. its orbit around the Sun is elliptical, and it takes roughly 160 000 years to complete an orbit. In other words, this comet has already made one or more passages around the Sun and may have been observed by prehistoric cavemen. This means that it has already survived close passages by the Sun, and will probably survive this one, too. If so, it may be the brightest comet of 2025. This comet reached perihelion on January 13, when it was also at its closest approach to the Earth. It was then at its brightest, almost as bright as Venus, but it was too close to the Sun for safe observations. On that evening the comet's head or coma was near the magnitude 3.9 star 44 Sagittarii.
By January 28 the comet was close to the magnitude 4 star 16 Psi Capricorni. By February 14 it was near the magnitude 4.5 star 14 Mu Piscis Austrini and fading rapidly. By March 1 the comet will be mid-way between magnitude 4.3 Beta Sculptoris and magnitude 2.4 Ankaa (Alpha Phoenicis).
You can track how bright Comet C/2024 G3 is by checking the
This periodic comet returns every 71 years, and is in our western twilight sky at present. Look due west, close to the horizon as soon as the sky darkens. On 16 July, the comet was near the magnitude 2.2 star Suhail (Lambda Velorum).
Comet C/2023 A3 (Tsuchinshan-ATLAS)
A potentially great comet is currently moving sunward, promising a spectacular show later this year. That comet, C/2023 A3 (Tsuchinshan-ATLAS), was discovered in January 2023, and astronomers soon realised it has the
potential to become truly dazzling. Predictions suggested that Tsuchinshan-ATLAS would at least as bright as the brightest stars in late September and early October this year, and in fact it reached first magnitude in
early October. Northern hemisphere observers had good views, but the comet's position was not favourable for those of us in the south. It passed almost directly between Earth and the Sun, and was difficult to find in the
constellation Sextans due to the nearby Sun's glare. By October 7 it had faded to magnitude 2.6 and was near the star Zaniah in the constellation Virgo. It is still very difficult to see in the twilight sky. By January 1 2025, it will have faded to magnitude
10.9 and will be near the star Altair (but still involved in the glow of twilight). For more information, click
This comet was discovered on 2 March 2022 at the Zwicky Transient Facility (ZTF) at the Hale Observatory on Mount Palomar. It was found on CCD images taken by
the famous 48-inch Schmidt Telescope. It was not very bright, and in the first weeks of February it was only faintly visible to the unaided eye from sites far from the light pollution of cities and towns.
The comet had two tails, the brighter being green in colour, probably due to the presence of diatomic carbon in its coma. Its last visit was 50 000 years ago, when it may have been observed by early aborigines. It made its closest approach
to Earth on February 2, when it was only 42 million kilometres away. On February 1 it was in the vicinity of the star Polaris (the 'North Star') which is never visible from Australia. In the following days it moved south, and was close to
the bright star Capella on February 5, but the tails were rapidly fading. Comet ZTF was in the vicinity of the planet Mars on February 10 and 11, when the photograph below was secured. It continued to move south, but is now
too far away to be seen. Comet ZTF (C/2022 E3) The same comet, photographed the following night, showing its rapid movement through the constellation Taurus.
Comet SWAN (C/2020 F8) and Comet ATLAS (2019 Y4)
Both of these comets appeared recently in orbits that caused them to dive towards the Sun's surface before swinging around the Sun and heading back towards the far reaches of the Solar System. Such comets are called 'Sun grazers', and their close approach to
the Sun takes them through its immensely powerful gravitational field and the hot outer atmosphere called the 'corona'. They brighten considerably during their approach, but most do not survive and disintegrate as the ice which holds them together melts. While
expectations were high that these two would emerge from their encounter and put on a display as bright comets with long tails when they left the Sun, as they came close to the Sun they both broke up into small fragments of rock and ice and ceased to exist. In December 2018, Comet 46P/Wirtanen swept past Earth, making one of the ten closest approaches of a comet to our planet since 1960. It was faintly visible to the naked eye for two weeks. Although
Wirtanen's nucleus is only 1.2 kilometres across, its green atmosphere became larger than the Full Moon, and was an easy target for binoculars and small telescopes. It reached its closest to the Sun (perihelion) on December 12,
and then headed in our direction. It passed the Earth at a distance of 11.5 million kilometres (30 times as far away as the Moon) on December 16, 2018.
Comet 46/P Wirtanen
Comet 12P Pons-Brooks
Comet 12P Pons-Brooks, photographed from Nambour at 6:40 pm on June 7, 2024.
Comet 46P/Wirtanen
Comet 46/P Wirtanen at perihelion on December 12, 2018, at 00:55 am. It was faintly visible to the unaided eye, but easily visible through binoculars. The circled star has a magnitude of 15.77, and the brighter one just to its left is GSC 60:1162, magnitude 13.8.
Comet Lulin
This comet, (C/2007 N3), discovered in 2007 at Lulin Observatory by a collaborative team of Taiwanese and Chinese astronomers, is now in the outer Solar System, and has faded below magnitude 15.
Comet Lulin at 11:25 pm on February 28, 2009, in Leo. The brightest star is Nu Leonis, magnitude 5.26.
The
LINEARNearly all of these programs are based in the northern hemisphere, leaving gaps in the coverage of the southern sky. These gaps are the areas of sky where amateur astronomers look for comets from their backyard observatories.
To find out more about current comets, including finder charts showing exact positions and magnitudes, click
here. To see pictures of these comets, click here.
The 3.9 metre Anglo-Australian Telescope (AAT) at the Australian Astronomical Observatory near Coonabarabran, NSW.
Deep Space
Sky Charts and Maps available on-line:
There are some useful representations of the sky available here. The sky charts linked below show the sky as it appears to the unaided eye. Stars rise four minutes earlier each
night, so at the end of a week the stars have gained about half an hour. After a month they have gained two hours. In other words, the stars that were positioned in the sky at 8 pm at the beginning of a month will have the same positions at 6
pm by the end of that month. After 12 months the stars have gained 12 x 2 hours = 24 hours = 1 day, so after a year the stars have returned to their original positions for the chosen time. This accounts for the slow changing of the starry
sky as the seasons progress.
The following interactive sky charts are courtesy of Sky and Telescope magazine. They can simulate a view of the sky from any location on Earth at any time of day or night between the years 1600 and 2400. You can also print an all-sky map. A Java-enabled web browser is required. You will need to specify the location, date and time before the charts are generated. The accuracy of the charts will depend on your computer’s clock being set to the correct time and date.
To produce a real-time sky chart (i.e. a chart showing the sky at the instant the chart is generated), enter the name of your nearest city and the country. You will also need to enter the approximate latitude and longitude of your observing site. For the Sunshine Coast, these are:
latitude: 26.6o South longitude: 153o East
Then enter your time, by scrolling down through the list of cities to "Brisbane: UTC + 10 hours". Enter this one if you are located near this city, as Nambour is. The code means that Brisbane is ten hours ahead of Coordinated Universal Time (UTC), which is related to Greenwich Mean Time (GMT), the time observed at longitude 0 degrees, which line passes through the eyepiece cross-hairs of the transit telescope at Greenwich Observatory in London, England. Click here to generate these charts.
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The first, circular chart will show the full hemisphere of sky overhead. The zenith is at the centre of the circle, and the cardinal points are shown around the circumference, which marks the horizon. The chart also shows the positions of the Moon and planets at that time. As the chart is rather cluttered, click on a part of it to show that section of the sky in greater detail. Also, click on Update to make the screen concurrent with the ever-moving sky.
The stars and constellations around the horizon to an elevation of about 40o can be examined by clicking on
The view can be panned around the horizon, 45 degrees at a time. Scrolling down the screen will reveal tables showing setup and customising options, and an Ephemeris showing the positions of
the Sun, Moon and planets, and whether they are visible at the time or not. These charts and data are from
YourSky, produced by John Walker.
The charts above and the descriptions below assume that the observer has a good observing site with a low, flat horizon that is not too much obscured by buildings or trees. Detection of fainter sky objects is greatly assisted if the observer can avoid bright lights, or, ideally, travel to a dark sky site. On the Sunshine Coast, one merely has to travel a few kilometres west of the coastal strip to enjoy magnificent sky views. On the Blackall Range, simply avoid streetlights. Allow your eyes about 15 minutes to become dark-adapted, a little longer if you have been watching television. Small binoculars can provide some amazing views, and with a small telescope, the sky’s the limit.
This month, the Eta Carinae Nebula is well placed for viewing, being two handspans above the south-eastern horizon at 7:30 pm. It culminates at 11 pm at mid-month, and is visible until dawn.
This description of the night sky is for 9 pm on March 1 and 7 pm on March 31. They start at Taurus, which is very low in the north-west. Most planets will not be available in the evenings this month - Mercury and Neptune are too close
to the Sun, and Saturn and Pluto are in the pre-dawn eastern sky. Mars and Jupiter are observable, as is Venus (but only in the first week and soon after sunset).
The Stars and Constellations for this month:
The largest planet, Jupiter, is visible in the evening sky this month. It is in Taurus and will be about a handspan above the north-western horizon. On March 1 it will set at 11:08 pm. At the end of March it will set at 9:24 pm. We will lose Jupiter from our evening sky on June 25, when it will be in conjunction with the Sun. The faint planet Uranus is in Aries and low to the horizon. It is about half-a-handspan to the left of the Pleiades star cluster. At mid-month it will set in the west-north-west at 9:04 pm. Uranus sets at 10 pm on March 1, so is not well placed for viewing this month.
On March 1, Orion (see below) is about two handspans above the west-north-western horizon. By mid-month, Orion will have set by 11:30 pm. Also at mid-month, Canis Major (the Large Dog) is just north of the zenith at 8 pm, with the brilliant white star Sirius (Alpha Canis Majoris) showing the Dog's heart. Sirius, also known as the Dog Star, is the brightest star in the night sky and is about a handspan north-west of the zenith. The brilliant white star Rigel (Beta Orionis) is about two handspans west of the zenith (or one-and-a-quarter handspans below Sirius).. Nearly overhead are the constellations Puppis, the Stern (of the ship, Argo) and Columba, the Dove. Columba culminates at 6 pm on March 15.
Sirius (Alpha Canis Majoris) is the brightest star in the night sky. It has been known for centuries as the Dog Star. It is a very hot A0 type star, larger than our Sun. It is bright because it is one of our nearest neighbours, being only 8.6 light years away. The four spikes are caused by the secondary mirror supports in the telescope's top end. The faintest stars on this image are of magnitude 15. To reveal the companion Sirius B, which is currently 10.4 arcseconds from its brilliant primary, the photograph below was taken with a magnification of 375x, although the atmospheric seeing conditions in the current heatwave were more turbulent. The exposure was much shorter to reduce the overpowering glare from the primary star.
The constellation Taurus with the clusters Pleiades and Hyades is between Orion and the north-western horizon. The brightest star in Taurus is a star dominating
(but not actually a member of) the Hyades cluster. This is Aldebaran, a K5 orange star with a visual magnitude of 0.87. It is only half as far away as the Hyades. The Pleiades is
a small group like a question mark, and is often called the Seven Sisters, although excellent eyes are needed to detect the seventh star without optical aid. All the stars in this cluster
are hot and blue. They are also the same age, as they formed as a group out of a gas cloud or nebula. There are actually more than 250 stars in the Pleiades.
The Pleiades is the small cluster at centre left, while the Hyades is the much larger grouping at centre right.
Wisps of a nebula through which the Pleiades are passing can be seen around the brighter stars in the cluster.
Between Orion’s head and the north-north-western horizon is a large constellation shaped roughly like a pentagon. It is north of Taurus. This is Auriga the Charioteer, its brightest star being Capella, at the bottom of the tilted pentagon.
Capella is the sixth brightest star in the sky, after Sirius, Canopus, Alpha Centauri, Beta Centauri and Vega. To the left of Capella is a small triangle of stars known as 'The Kids’. The lowest star in this triangle is Epsilon Aurigae, one of the
largest stars known. It is also very distant.
The top star of Auriga's pentagon is actually in the constellation Taurus. It is El Nath, also known as Beta Tauri. It marks the tip of the Bull's western horn. Coincidentally, Jupiter is this month sitting between the two horns of Taurus, near the star Aldebaran.
To the east of Auriga, Gemini is quite high, the two twin stars at its eastern end, Pollux and Castor being due north. At 9 pm at the beginning of the month they are straddling the meridian (the line that runs from due south to due north and passing through the zenith - directly overhead). When a sky object crosses the meridian, it is said to be culminating. At that point, it ceases rising and begins setting. The Twins will have set by 1 am at mid-month. This month, the planet Mars forms a triangle with the stars Pollux and Castor.
Tonight, at a little over two handspans above the northern horizon, and directly above Pollux and Castor, is the first magnitude star Procyon, which is the brightest star in the constellation Canis Minor (the Small Dog).
High in the north-east is another zodiacal constellation, Leo, the Lion. The bright star Regulus (Alpha Leonis) marks the Lion’s heart, and Denebola, the star marking the tip of the lion's tail, is low in the east-north-east. From the southern hemisphere, we always see the Lion upside-down. His head and mane are marked by a curved line of stars shaped like an upside-down question mark. This line is also known as the 'Reaping Hook' or 'Sickle', the star Regulus marking the end of the Sickle's handle.
Between Gemini and Leo is the faint constellation of Cancer the Crab. Though a fairly unremarkable constellation in other ways, Cancer does contain a large star cluster called Praesepe or the Beehive, which presents well in binoculars. Also known as M44*, Praesepe is a little more than halfway along a line between Pollux and Regulus.
Rising above the eastern horizon is the next zodiacal constellation after Leo, Virgo, the Virgin. The brightest star in Virgo is Spica, an ellipsoidal variable star whose brightness averages magnitude 1. This makes it the sixteenth brightest star, and its colour is blue-white. Spica is about 10 degrees above the theoretical eastern horizon at this time. Between Denebola and Spica is a fainter star, Porrima, which has a magnitude of 2.74.
High in the east above Spica is the constellation Corvus the Crow, shaped like a quadrilateral of magnitude 3 stars. A large but faint constellation, Hydra, the Water Snake, winds its way from near Procyon around the north-eastern part of the sky at an altitude of about 60 degrees above the horizon. It passes over the top of Corvus and Virgo to end near Libra, which will not rise until 10 pm (at the beginning of the month).
Hydra has one bright star, Alphard, mv=2.2, an orange star that was known by Arabs in ancient times as ‘The Solitary One’, as it lies in an area of sky with no other bright stars nearby. Alphard culminates at 9:45 pm at mid-month.
Well up in the south-south-east, Crux (Southern Cross) is almost horizontal. The two Pointers Alpha and Beta Centauri lie below Crux. Crux will have rotated clockwise to a vertical position by 1:15 am at mid-month. Surrounding Crux on three sides is the large constellation Centaurus, and between Crux and the southern horizon are two brilliant stars, Alpha and Beta Centauri. Beta is the one nearer to Crux. These two stars are also known as the Guardians of the Cross.
Crux is at centre, lying horizontally. Beneath Crux lies the Coalsack. Towards the bottom are the two Pointers, Alpha and Beta Centauri. At top centre is the Eta Carinae nebula, also shown below.