Skynotes September 2012

Month Highlights

Venus and Jupiter continue to shine brightly in the early morning sky. Mars and Saturn are now drifting apart in the western sky at sunset. By the end of the month Mercury can be found near Saturn, low to the western horizon.

Planetarium Event - Beneath Australian Skies

The Melbourne Planetarium at Scienceworks will host a special evening lecture at 7:30pm, Thursday 13th September. Visiting expert, Paul Curnow from Adelaide Planetarium, will share star stories from indigenous groups across Australia. The evening will include a glass of wine with cheese, the opportunity to chat to Paul as well as to the Planetarium’s astronomer, Dr Tanya Hill, and to be immersed in a planetarium experience. You will finish the evening stargazing through telescopes (weather permitting).

For more information, pricing or bookings please see the What's On listing.

September School Holidays

Scienceworks will be opened daily from 10am–4:30pm during school holidays (22nd September – 7th October). 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: The Problem with Pluto – travel on a research craft to the outer regions of our Solar System.

2pm: Tilt – come on a whirlwind adventure to find out how seasons work.

3pm: Black Holes: Journey into the Unknown – where the unimaginable becomes reality.

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

Sunrise & Sunset Times

 Moon Phases

The Moon will be at apogee (furthest from Earth) on Friday 7th at a distance of 404,295 km.

The Moon will be at perigee (closest to Earth) on Wednesday 19th at a distance of 365,748 km.

Let the Moon Be Your Guide

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

• On the morning of the 7th, the Moon is near the star cluster Pleiades (Taurus).
• The Last Quarter Moon sits to the right of Jupiter on the morning of the 9th.
• Before sunrise on the 13th the crescent Moon is near Venus.
• The waxing crescent Moon sits between Saturn and Spica (Virgo) after sunset on the 18th.
• On the 20th the Moon can be found above the red planet Mars.
• Then on the 21st the Moon is near the red supergiant star Antares (Scorpius).

Planets

Mercury appears above the western horizon during the last week of the month. It can be seen at sunset below the bright star Spica (Virgo).

Venus is low to north-east horizon at sunrise. During the early part of the month, the twin stars of Gemini, Castor and Pollux, can be found to the left of Venus. The Moon sits alongside Venus on the morning of the 13th.

Earth days are warming up again as we pass the Spring Equinox on Sunday 23rd. At 12:49am the Sun crosses the celestial equator heading south. While it is often said that day and night are equal on the equinox, this is not quite so. It is only the centre of the Sun that is above the horizon for 12 hours; our day is slightly longer at 12 hours and 8 minutes. That’s partly because the day starts with the first appearance of the Sun, but there’s another strange effect going on as well. The Earth’s atmosphere bends light from the Sun so that at sunrise we happen 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. So on that basis, when is day and night equal? On Wednesday 19th, a few days before the equinox.

Mars can be found in the western sky at sunset. The thin crescent Moon sits below Mars on the evening of the 19th.

Jupiter is shining brightly in the north during the early hours before sunrise. It sits below the triangle shape of Taurus, the bull and to the left of Jupiter is the beautiful star cluster Pleiades. The Last Quarter Moon is near Jupiter on the morning of the 9th.

Saturn makes its way towards the western horizon this month. The bright star Spica (Virgo) can be found sitting to the left of Saturn. On the 18th the crescent Moon joins the pair. Then on the 30th, Mercury can be seen below Spica, with Saturn above and to the right.

Meteors

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:

7:32pm - 7:36pm, Sunday 9th September.

The space station will appear in the north-west and will disappear as it travels 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 1979, Pioneer 11 (USA) made the first flyby of Saturn and returned the first close-up images of the planet.

5th 1977, Voyager 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 1985, ICE (USA) became the first craft to encounter a comet (Comet Halley).

14th 1959, Luna 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 1977, Voyager 1 (USA) returned the first image of the Earth and the Moon together.

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

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