Voyager 1 resumes its mission 

Last November, the 47-year old space probe Voyager 1 stopped sending data back to Earth 24 billion kilometres away. A faulty chip was blamed, but on 20 April NASA engineers succeeded in some clever long-distance software reprogramming. Now the intrepid probe (illustrated above) is again transmitting updates on its “health and status”. It is hoped it can resume sending science data from the few instruments still operating.

Its illustrious twin, Voyager 2, launched in October 1977 on its Grand Tour, flew by Jupiter, Saturn, Uranus and Neptune on its way out of the solar system. Voyager 1, launched one month earlier, passed by Jupiter and Saturn before taking a different path up and out of the plane of the solar system. Both probes gave us the first close up views of the four outer planets, their rings and many moons, and are now in interstellar space beyond the Sun’s region of influence, the heliosphere. Truly, the Voyagers are living up to their names, and are spacecraft that keep on giving. In about another decade their power supplies are expected to drop too low for any further communication back to Earth, after which they will travel indefinitely on into the galaxy.

And both spacecraft carry with them on their journey a Golden Record, the sounds of Earth.

Explore more at:

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Melbourne Sun times

Daylight Savings ends 3am, Sunday 7 April, with clocks turned back 1 hour.

Date	Rise	Set	Day length	Solar noon*
Wednesday 1st	7:01am	5:32pm	10:31hours	12:17pm
Saturday 11th	7:10am	5:22pm	10:12hours	12:16pm
Tuesday 21st	7:18am	5:14pm	9:56hours	12:16pm
Thursday 31st	7:25am	5:09pm	9:43hours	12:17pm

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

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Moon phases

Phase	Date
Third Quarter	Wednesday 1st
New Moon	Wednesday 8th
First Quarter	Wednesday 15th
Full Moon	Thursday 23rd

Moon distances

Lunar perigee (closest to Earth) is on Monday 6th at 363,163 km.

Lunar apogee (furthest from Earth) is on Saturday 18th at 404,640 km.

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Planets

The planets are ‘wanderers’ (planeta from ancient Greek) moving along their obits and we can notice them shift their positions against the fixed background of distant stars. Inner planets orbit the Sun faster with shorter years than outer planets which are slower having longer years. The nightly change of position of inner planets, like Mars and Venus, are more obvious than the outer planets, such as Jupiter and Saturn.

Mercury is nearing its greatest elongation (its highest position in our skies). It is visible from 5 am early in the month, rising rise a little later and reaching a slightly lower position during the month before being lost in the dawn light.

Venus is about to move behind the Sun and is not visible this month. Once it completes its passage around the Sun it will return in August in the west after sunset as the ‘evening star’.

Mars has returned from its brief trip behind the sun and is visible again from 3:30am as it rises in the north-east.

Jupiter has been nearing the Sun from our perspective and not visible. It is about to pass behind the Sun for its solar conjunction. It will reappear in June in the east around 5:30am.

Saturn is back from its solar conjunction behind the Sun and rises from 2am early in the month, and then a little earlier each morning until from 1am at month’s end.

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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:

Evening

Thursday 2nd 6:54pm to 6:58pm south-west to east-south-east

Sunday 5th 6:02pm to 6:08pm south-west to north-east

Morning

Friday 17th 6:19am to 6:26am north-west to south-east

Sunday 19th 6:16am to 6:21am west to south-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 1991, Helen Sharman, the first Briton in space, blasts off onboard a Soyuz spacecraft.

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.