Melbourne Sun times

Date	Rise	Set	Day length	Solar noon§
Monday 1st	7:00	5:33	10:33 hours	12:17
Tuesday 11th	7:09	5:23	10:13 hours	12:16
Sunday 21st	7:17	5:15	9:57 hours	12:16
Wednesday 31st	7:25	5:09	9:44 hours	12:17

§ When the sun is at its highest, crossing the meridian or local longitude.

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Moon phases

Phase	Date
Full Moon	Saturday 6th
Third Quarter	Saturday 13th
New Moon	Saturday 20th
First Quarter	Sunday 28th

Moon distances

Lunar perigee (closest to Earth) is on Tuesday 11th at 369,343km.

Lunar apogee (furthest from Earth) is on Friday 26th at 404,509km.

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Planets

The planets are ‘wanderers’ (planeta from ancient Greek) moving along their obits such that night by night we see them shift their positions against the fixed background of distant stars. The closer a planet is to the Sun the faster it orbits and the shorter its year, and the further out the slower it is and the longer its year. For this reason, the nightly change of position of inner planets, like Mars and Venus, will be more obvious than the outer planets Jupiter and Saturn.

However, the inner terrestrial planets are not orbiting entirely alone. It is now better understood that the solar system is ‘growing’ in terms of objects in orbit around the sun. It is not just newly discovered bodies in the main asteroid belt beyond Mars or in the near-Earth region, nor in the distant Kuiper Belt beyond Neptune, but new material in the inner solar system as well.

In fact, the Parker Solar Probe has detected a vast dust ring orbiting with Venus, seen in this view below as a faint line running from lower left to upper right. The sun is blocked out at centre, and the bright spots are Earth at left and Mercury and Venus at right). The rough band running top to bottom between Earth and Sun is the distant band of the Milky Way.

Some of the inner planets are accompanied in their orbits by dust and small asteroids that they have ‘gathered’ gravitationally and that co-orbit with them, as represented in this illustration:

Explore

NASA – Inner Solar System’s Dust

Solar Probe Sees Venus Dust Ring

Mercury is a daytime object this month and being close to the sun it is not visible.

Venus is the ‘evening star’ as present appearing soon after sunset in the north-west at dusk from 5.30pm until it sets by 8pm.

Mars can be seen from early evening around 6pm in the north before setting by 9.30pm.

Jupiter is not visible this month as, after its recent passage behind the sun, it is a daytime object in our skies.

Saturn will be visible in May as an early morning planet from 1am before it becomes lost by 6.30am in the dawn light.

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Meteors

The Eta Aquarids meteor shower begins on the 3rd peaking on the 6th. The shower is linked to Comet Halley and rates can reach 55 meteors per hour. They are sand or rice grain size, very fast at 64km/sec, usually yellow with persistent trains, and enter the atmosphere 100km above the surface. They appear in the constellation Aquarius, and the radiant, or point from which they appear to originate, rises at 2.30am moving higher to the north-east by dawn.

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Stars and constellations

In the west

The brightest star in the night sky, Sirius, is high in the west and forms the principal star in Canis Major (Greater Dog), a companion to Orion, the hunter who lies below much closer to the western horizon and appears almost upside down from our southern hemisphere view. Marking one of his shoulders is Betelguese, a very obvious red giant star, and diagonally across Orion to the upper left is Rigel, a blue supergiant star that makes a contrast. The three bright stars that form an almost vertical line in the centre of Orion are his belt. His belt is also the base of the ‘Saucepan’ asterism. His scabbard or sword that angles up from his belt forms the saucepan’s handle. In the centre of the handle or sword/scabbard is a fuzzy greenish object which binoculars or telescopes will reveal as the glorious Orion Nebula some 1300 light years from us – a vast cloud of gas and dust where young stars are forming.

Above and to the south of Sirius is Canopus, the second brightest star in the night sky which belongs to the constellation Carina (the keel).

In the north

In the north is the constellation of Leo, the lion. Leo is upside down compared to the northern hemisphere. Look for an upside-down question mark as his head and mane. The brightest star in Leo is Regulus, meaning ‘little king’.

In the south-east

The large and impressive constellation of Scorpius can now be seen rising horizontally in the south-east with its head and pincers reaching east and the long curving tail stretching to the south. The scorpion's heart is marked by the red star Antares. This is a very rich area of the Milky Way and the scorpion's tail contains beautiful star clusters that can be seen with binoculars.

The two bright Pointers (Alpha and Beta Centauri in the constellation of Centaurus) are low in the south-east and lead your eye up to the smallest constellation astronomers use – Crux (or Southern Cross) which sits on its side this month and easily recognisable.

In less light-polluted skies you can see the pale band of light that arcs across the entire sky from south-east to north-west, the Milky Way, made of billions of distant stars and vast interstellar dust clouds that form much of the galaxy.

In the south-west

Out on their own in the south-west lie the intriguing Large and Small Clouds of Magellan, two small nearby galaxies with names derived from Fernão de Magalhães, the famous Portuguese explorer of the 16th century who attempted the first circumnavigation of the globe, and better known in Spanish as Ferdinand Magellan.

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International Space Station

ISS orbits every 90 minutes at an average distance of 400 km appearing like a bright star moving slowly across the night sky. Here are some of the brightest morning and evening passes expected this month over Melbourne and Central Victoria:

Morning

• Saturday 20th, 6.24am-6.31am, West-North-West to South-east.

Evening

• Friday 5th, 6.47pm-6.51pm, South-West to East-North-East

Heavens Above gives predictions for visible passes of space stations and major satellites, live sky views and 3D visualisations. Be sure to first enter your location under ‘Configuration’.

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On this day

1st 1958, Van Allen radiation belts were discovered - concentrations of electrically charged particles surrounding the Earth influenced by its magnetic field.

1st 1930, Pluto’s name is confirmed by Lowell Observatory after a suggestion by British 11-year old Venetia Burney.

1st 1910, birth of astrophysicist J Allen Hynek who investigated reports of unidentified flying objects for the US Air Force under ‘Project Blue Book’.

4th 1675, Royal Greenwich Observatory is established by decree of King Charles II.

5th 1961, Alan Shepard Jr (Mercury 3), the first American to be launched into space.

9th 1979, Pioneer Venus 2 craft sent five probes into the atmosphere of Venus.

11th 1916, Albert Einstein’s ‘General Theory of Relativity’ was first presented.

12th 1965, Luna 5 (USSR) crashes on Moon.

13th 1861, one of eight 19th century ‘Great Comets’ is discovered by John Tebbut.

14th 1973, Skylab 1, USA’s first space station was launched.

15th 1618, the Third Law of Planetary Motion, establishing a direct relationship between distance from Sun and orbital period, is determined by Johannes Kepler. 

16th 2011, Space Shuttle Endeavour (USA) launched on its 25th and final mission.

17th 1969, Venera 6 (USSR) sends data for 51min before failure due to extreme pressure while descending by parachute to the surface of Venus. 

18th 1969, Apollo 10 (USA), the fourth crewed Apollo, launched an 8 day full rehearsal mission without a moon landing. It sent the first colour TV to Earth and orbited the moon 31 times. With Command Module ‘Charlie Brown’ in orbit, Lunar Module ‘Snoopy’ flew for two hours in four orbits coming to14km of the surface after which its descent (lower) stage was jettisoned to eventually crash on the moon, and later its ascent (upper) stage was sent into space to orbit the sun.

18th 2005, Pluto’s moons Nix and Hydra are seen by Hubble Telescope before New Horizons’ (USA) later discovery of two more, Styx and Kerberos.   

19th 1961, Venera 1 (USSR) makes first pass of a planet (in this case Venus) although contact with Earth by then had been lost.

20th 1990, Hubble Space Telescope sent its first photograph from space, an image of a double star 1,260 light years away.

21st 2010, launch of IKAROS spacecraft (Japan), the first successful solar sail technique used for planetary travel.

25th 1961, President John F. Kennedy launches the USA’s race to the Moon.

25th 240 BCE, first recorded close pass by the Sun (perihelion) of Comet Halley. 

28th 1959, monkeys Abel and Baker are sent on sub-orbital flight of 580 km into space in the nose-cone of a Jupiter rocket.

28th 585 BCE, solar eclipse occurs during a battle between Medes and Lydians. Knowledge of past eclipses has enabled dating of other historical events.

28th 2002, water ice on the Red Planet is discovered by Mars Odyssey (USA).

29th 1919, Einstein’s ‘General Theory of Relativity’ is confirmed by Arthur Eddington’s study of distant star light bending during a total solar eclipse.

29th 1794, birth of the first astronomer to map the Moon and Mars, Johann von Mädler.

30th 1975, European Space Agency (ESA) is created by merging Launch Development and Space Research organisations.

30th 1966, launch of Surveyor 1 (USA) which will make the first landing on another body; in this case, the Moon.