Skynotes August 2009

Month Highlights

The two gas giants, Jupiter and Saturn, can be found in opposite parts of the sky after sunset. Jupiter is rising in the east, while Saturn is setting in the west. The faint planet Mercury joins Saturn in the western sky. Mars and Venus can be seen in the early morning towards the north-east.

International Year of Astronomy

The International Year of Astronomy celebrates 400 years since Galileo first pointed a telescope at the night sky. It was on the 25th August that Galileo demonstrated his telescope to the lawmakers of Venice with great success.

Planetarium Events

Discover the Night Sky – August 2009

The Melbourne Planetarium at Scienceworks presents special after-dark sessions, Thursday evenings from 6 to 27 August at 7pm. All evenings include complementary wine and cheese, the opportunity to chat to the Planetarium’s Astronomer and be immersed in a planetarium experience. You will finish the evening stargazing through telescopes (weather permitting).

Each evening will showcase a different aspect of the night sky. For more information, pricing or bookings see the What's On listing or call the Scienceworks Booking Office on 9392 4819 between 9am and 4.30pm, Monday to Friday.

Sunrise and Sunset Times

Moon Phases

The Moon will be at apogee (furthest from Earth) on Tuesday 4th, at a distance of 406 026 km.
The Moon will be at perigee (closest to Earth) on Wednesday 19th, at a distance of 359 641 km.

Let the Moon be Your Guide

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

• On the night of the 1st the waxing gibbous Moon can be found near Scorpius.
• On the night of the 6th the Full Moon travels across the sky with Jupiter.
• Before sunrise on the 14th the Last Quarter Moon sits to the left of the star cluster Pleiades.
• During the early hours of the 16th the waning crescent Moon is near Mars.
• Before sunrise on the 18th the crescent Moon is just below Venus.
• Just after sunset on the 22nd the waxing crescent Moon sits to the left of Mercury, with Saturn below.
• During evening twilight on the 24th the crescent Moon sits near Spica (Virgo).
• On the night of the 27th, the First Quarter Moon lies at the head of Scorpius.  

Planets

Mercury begins to appear out of the glow of sunset. It can be seen above the western horizon, near the bright star Regulus. As the month goes by Mercury moves higher in the sky to meet up with the planet Saturn. After sunset on the 16th, Mercury can be found directly to the left of Saturn. On the 22nd, the thin crescent Moon sits just below Mercury.

Venus can be found in the north-east before sunrise. Above and to the left of Venus is the red planet Mars. On the morning of the 18th the thin crescent Moon sits just below Venus. At the end of the month the twin stars of Gemini, Castor and Pollux, can be found to the left of Venus.

Mars is also in the north-east before sunrise. It makes a trio of red objects in the early morning sky. Sitting above Mars is the red giant star Aldebaran (Taurus) and to the right is the red supergiant star Betelgeuse (Orion).  On the morning of the 16th the crescent Moon sits below Mars.

Jupiter reaches opposition on the 15th, which means that it is on the opposite side of the Earth from the Sun. As a result, Jupiter is in the sky for the entire night, rising in the east at sunset and setting in the west at sunrise. It also means that Jupiter is in the darkest part of the night sky and therefore is at its brightest. Invisible to the naked eye, the planet Neptune is near Jupiter and reaches opposition on the 18th. On the night of the 6th the Full Moon travels across the sky with Jupiter.

Saturn has been the planet to see in the evening sky but it is now drifting towards the western horizon at sunset. It sits to the right of Mercury on the 16th.

Meteors

The major meteor shower this month is the Perseids, which peaks on the 13th. This is a strong Northern Hemisphere shower with around 100 meteors predicted per hour. It resides within the northern constellation of Perseus and is difficult to view from the Southern Hemisphere. However, it has been known for long-pathed Perseids to be seen here at the peak of the shower.

Perseids are fast, bright and frequently leave persistent trails. They appear to come from a point below the north-eastern horizon. The best time to look for Perseids is from 3am onwards. This shower is associated with Comet Swift-Tuttle, which passed near the Sun in 1991.

Stars and Constellations

The two dominant constellations that sit high in the sky this month are Scorpius (the scorpion) with its hook-shaped tail and bright, red star Antares, and Sagittarius (the archer) whose brighter stars form a shape that resembles a teapot.

Crux, or the Southern Cross, is high in the south-west. On a clear, moonless night it may be possible to see the Coal Sack nebula, a dark region that lies between the two brightest stars of the Cross, Alpha and Beta Crucis.

Low in the southern sky are the bright stars Achernar (to the east) and Canopus (to the west). These stars lie opposite the Southern Cross and never disappear below the horizon.

International Space Station

From Earth, the ISS appears as a bright star that steadily moves across the sky. It can often be seen from Melbourne, for example at:

6:15pm – 6:21pm, Thursday 13th August.

The Station will first appear above the north-west horizon, travelling past Saturn and Mercury before disappearing in the south-east near Jupiter.

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

On This Day

4th 1971, Apollo 15 (USA) launches the first satellite into lunar orbit from a manned craft.

5th 1962, a lunar occultation enabled Australian radio astronomers to determine that the radio source 3C 273 in Virgo was located far beyond our Galaxy, heralding the discovery of the first Quasar.

5th 1998, the Near Earth Object Program Office is set up by NASA to detect and catalogue asteroids that approach near to Earth.

6th 1996, NASA announces that a meteorite uncovered in Antartica contains evidence of primitive life on Mars.

7th 1959, Discoverer 1 (USA) returns the first satellite images of the Earth.

10th 1877, American astronomer Asaph Hall discovered Mars’ moon Deimos and two days later Mars' second moon Phobos.

12th 1999, the first observations are made with the Chandra X-Ray Space Observatory (USA).

13th 1642, Christiaan Huygens discovered the Martian south polar cap.

14th 1994, the Hubble Space Telescope photographs Uranus with rings.

19th 1960, two dogs, Belka and Strelka, were launched into space aboard Sputnik 5 (USSR) and successfully returned to Earth.

20th 1977, Voyager 2 (USA) is launched to explore the planets in the outer Solar System.

22nd 1989, the first complete ring around Neptune was discovered.

23rd 1966, the Lunar Orbiter 1 took the first photograph of the Earth from the Moon.

24th 1989, Voyager 2 (USA) makes the first flyby of Neptune and returns the first close-up images of the blue planet.

25th 1609, Galileo demonstrated the newly invented telescope.

27th 1999, the Mir Space Station’s (Russia) final permanent crew return to Earth.

28th 1993, the Galileo spacecraft (NASA) discovers Dactyl, the first moon to orbit an asteroid (Ida).

31st 1971, Dave Scott (USA) became the first person to drive a car on the Moon.

31st 1979, Comet Howard-Koomur-Michels is the first recorded comet to collide with the Sun.