Skynotes September 2016


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Month Highlights

It’s the last chance to see all five planets in the night sky. There will be a lovely grouping low to the west on the 3rd. Venus, Jupiter, Mercury and the crescent Moon will be visible just after sunset. However, over the following evenings Jupiter and Mercury will disappear below the horizon, moving too close to the Sun to be seen.

Mars and Saturn can be found high in the western sky after sunset. The two planets are quickly drifting apart and the First Quarter Moon will come between them on the night of the 9th.

Planetarium Events

AstroLight 2016 - September 10

Scienceworks is hosting a festival celebrating astronomy and light. This family event will include talks, hands-on demonstrations, stargazing through telescopes, plus a fabulous guest speaker - former NASA astronaut, Marsha Ivins. For event details see the What's On.

Astrobites: Exoplanets and Life Elsewhere

Join astrobiologist, Dr Jonti Horner, on 24th September to hear about the search for exoplanets (planets orbiting distant stars) and the potential for finding life beyond our Solar System. For event details see the What's On.

Spontaneous Fantasia - October 8

In Australia, for the first time, multimedia artist J-Walt will perform his extraordinary work – a live VR musical performance. Using improvised real-time computer graphics J-Walt creates entire worlds that unfold before the audience. For event details see the What's On.

September School Holidays

Scienceworks will be opened daily from 10am–4:30pm during the school holidays (September 17 - October 2). Planetarium session times are:

12pm: Tycho to the Moon – meet Tycho, a dog who doesn’t just howl at the Moon but wants to go there!

1pm: Tilt – come on a whirlwind adventure to find out how the seasons work.

2pm: Capturing the Cosmos – discover how astronomers today are exploring the universe on a grand scale.

3pm: Starlight – uncover the mysteries of the stars and the curiosity they inspire.

See the Melbourne Planetarium's What's On listing for more details.

Sunrise & Sunset Times

Date Rise Set
Thursday 1st 6:42 5:59
Sunday 11th 6:27 6:07
Wednesday 21st 6:11 6:16
Friday 30th 5:57 6:23

Moon Phases

Phase Date
New Moon Thursday 1st
First Quarter Friday 9th
Full Moon Saturday 17th
Last Quarter Friday 23rd

The Moon will be at apogee (furthest from Earth) on Wednesday 7th at a distance of 405,057 km.

The Moon will be at perigee (closest to Earth) on Monday 19th at a distance of 361,893 km.

Let the Moon Be Your Guide

The Moon can be used as a pointer to find other objects in the sky.

  • An annular solar eclipse occurs on the 1st, but it is only visible from Central Africa and Madagascar.
  • After sunset on the 3rd, the waxing crescent Moon is low to the western horizon with Mercury, Jupiter and Venus.
  • The crescent Moon sits above Venus on the 4th.
  • Then on the 5th, the crescent Moon is to the right of Spica (Virgo, the maiden).
  • The First Quarter Moon comes between Mars and Saturn on the 9th.
  • On the 14th, the waxing gibbous Moon sits between Altair (Aquila) and Fomalhaut (Piscis Austrinus).
  • During the early hours of  the 22nd, the waning gibbous Moon is near Aldebaran (Taurus, the bull).
  • The waning crescent Moon sits above the twin stars of Gemini, Castor and Pollux, on the morning of the 25th.
  • Before sunrise on the 28th, the crescent Moon is close to Regulus (Leo, the lion).


Mercury is very low to the western horizon after sunset and only visible for the first few evenings of September before it moves too close to the Sun to be seen.

Venus continues to shine brilliantly in the western sky throughout the month. It is just above the faint crescent Moon on the 3rd, with Jupiter and Mercury low to the western horizon. On the 19th, it pairs up with the bright star Spica (Virgo, the maiden) which sits just to the left of Venus.

Earth days are warming up again as we pass the Spring Equinox on Friday 23rd. At 12:21am the Sun crosses the celestial equator heading south. It is often said that day and night are equal on the equinox, but this is not quite so. Only the centre of the Sun is above the horizon for 12 hours, making our day slightly longer at 12 hours and 8 minutes. Not only does the day start with the first appearance of the Sun, but there’s another strange effect occurring as well. The Earth’s atmosphere bends light from the Sun so that at sunrise we are able to see the Sun before it physically crosses the horizon. The reverse occurs at sunset, we continue to see the edge of the Sun for several minutes even though it has already sunk below the western horizon. When is day and night equal? On Monday 19th, a few days before the equinox.

Mars and Saturn can be found high in the western sky after sunset. At the start of the month, they form a triangle with the red supergiant star Antares (Scorpius). As the month goes by, the two planets drift apart. The First Quarter Moon comes between them on the 9th. By the end of the month, Venus, Saturn and Mars are found in a line stretching across the western sky.

Jupiter is quickly moving towards the western horizon and is only visible for a few evenings at the start of the month.


September is a poor month for meteors. The Southern Piscids is the most active shower and while it has an extended peak which runs from the 11th to the 20th, it only produces a few meteors per hour. The meteors appear near the constellation of Pisces (the fish) which can be found in the north-west from midnight until dawn.

Stars & Constellations

In the early evening, the Southern Cross can be seen in the south-west, tipped over on its side, with the Two Pointers almost vertical above it. Above the western horizon sits the star Spica in the constellation of Virgo and in the north-west is the orange giant star Arcturus that belongs to Bootes, the herdsman.

Turning towards the south-east we see the bright star Achernar, which marks the end of the river, Eridanus, and also Fomalhaut, the brightest star in Piscis Austrinus. High in the north are the three main stars of Aquila, the Eagle, including the bright star Altair, while low to the horizon is Vega, the fifth brightest star in the night sky.

Directly overhead at sunset, the curl of the Scorpion’s tail can be seen near the teapot shape of Sagittarius. The Milky Way spans the sky overhead, looking splendid as it stretches almost north-south.

International Space Station

The ISS orbits the Earth every 90 minutes at an average distance of 400 km. From Earth, it appears as a bright star that steadily moves across the sky. It can often be seen from Melbourne, for example at:

7:40pm - 7:43pm, Friday 16 September.

The Station will appear above the south-west horizon and travel up towards Mars and Saturn before disappearing overhead.

Predictions of when to see the ISS can be obtained from the Heaven's Above website.

On this Day

1st 1939, Oppenheimer and Snyder publish the first paper that describes black holes.

1st 1979Pioneer 11 (USA) made the first flyby of Saturn and returned the first close-up images of the planet.

5th 1977Voyager 1 (USA) was launched to explore the outer Solar System.

8th 1966, the first episode of Star Trek was shown.

9th 1839, John Herschel made the first ever glass plate photograph.

11th 1985ICE (USA) became the first craft to encounter a comet (Comet Halley).

14th 1959Luna 3 (USSR) became the first craft to fly to and impact another celestial body, the Moon.

15th 1997, the Mars Global Surveyor (USA) discovered a weak magnetic field around Mars.

18th 1977Voyager 1 (USA) returned the first image of the Earth and the Moon together.

23rd 1846Neptune was discovered by Johann G. Galle (Germany).

27th 1905, Albert Einstein submits the paper containing the famous equation E=mc2.