Skynotes February 2013

Month Highlights

The two gas giants, Jupiter and Saturn, are the best planets for viewing this month. And for something different, we also take a look at some special asteroids and comets.

Astronomical Highlights

Flyby of Asteroid 2012 DA14

On the morning of 16th February, the asteroid 2012 DA14 will zoom by Earth. Its closest approach, at 6.26am, will bring it just 27,700km from us. That’s closer than the geosynchronous satellites – a ring of communication and weather satellites orbiting the Earth at 36,000km. The good news is, there’s virtually no chance of any collisions occurring. And, of course, the asteroid will be much too far away to affect Earth.

2012 DA14 is about 50m wide, so it’s not a very large one, but it’s not that small either. It won’t be visible to the naked eye but experienced observers might be able to catch a glimpse with a telescope. It will be in the south, just below the Southern Cross. The hard thing will be pin-pointing it while it’s moving so fast.

Comets for 2013

There’s been quite a bit of buzz around that 2013 will be the year for spectacular comets. But comets are finicky creatures. They can burst into view almost without warning, while others never reach their dazzling potential.

Here’s the latest on three interesting ones.

Comet Lemmon is a special one for us because it is currently moving right pass the south celestial pole. It may become faintly visible to the naked eye later this month.

Comet PANSTARRS will be at its closest to the Sun in early March and while it was initially estimated that the comet could brighten considerably, things are no longer looking as good. Even if it does brighten later in March the comet is only visible during evening twilight, so it’s likely to be reasonably faint.

Comet ISON is the comet that everyone is waiting for, with some even making the bold suggestion that it might become briefly visible during the day. It’s a sungrazing comet and will fly through the Sun’s atmosphere on 28 November. It could become dazzling or it could fizzle away, with comets you just never know. And unfortunately most of the action will take place in the northern hemisphere.

If any of these comets do brighten up, updates will be posted on the Museum Victoria blog.

Sunrise & Sunset Times

Moon Phases

The Moon will be at apogee (furthest from Earth) on Tuesday 19th at a distance of 404,473 km.

The Moon will be at perigee (closest to Earth) on Thursday 7th, at a distance of 365,313 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 2nd the waning gibbous Moon is near Spica (Virgo).
• Then on the 3rd, the Last Quarter Moon sits between Spica and Saturn.
• While on the 4th, the Moon is next to Saturn.
• The waning crescent Moon is near Antares (Scorpius) on the morning of the 5th.
• Before sunrise on the 9th, the thin crescent Moon sits just above Venus.
• After sunset on the 17th, the Moon is to the left of the star cluster Pleiades.
• On the 18th the the First Quarter Moon is very close to Jupiter.
• On the evening of the 25th, the Moon travels across the sky with Regulus (Leo, the lion).

Planets

Mercury appears briefly above the north-west horizon at the start of the month. It can be seen directly to the right of Mars after sunset on the 9th, but they are very low to the horizon and disappear just a few days later.

Venus is above the eastern horizon during early morning twilight. On the morning of the 9th, the thin crescent Moon is just above and to the left of Venus.

Mars disappears into the twilight at the start of the month. It can be seen with Mercury, very close to the north-west horizon after sunset. Interestingly, Mercury is actually brighter than Mars. That’s because Mars is currently quite distant to us. It is about 350 million km away, not too far off its maximum distance of 400 million km from Earth.

Jupiter continues to shine brilliantly in the north-west. Just above Jupiter is the triangular shape of Taurus the bull. The bright red star Aldebaran marks the bull’s glowing red eye. On the night of the 18th the First Quarter Moon is right next to Jupiter.

Saturn is high in the north at sunrise, trailing behind the bright star Spica (Virgo). During the early hours of the morning, you can also see the magnificent Scorpius following behind. On the morning of the 3rd the Moon comes between Spica and Saturn.

Meteors

The alpha-centaurids and beta-centaurids are active from the 2nd through until the 25th, with a peak on the 8th. The two showers have distinct characteristics, but in practice it is difficult to distinguish between them. These showers are perfect for us as they occur near the bright Two Pointers that lead the way to the Southern Cross. Although the showers are not generally strong, they often produce many bright meteors including some fireball types and some leave fine persistent trails. On good occasions rates of 25 meteors per hour have been recorded although lower rates of around 6 meteors per hour have been more usual in the last decade.

Stars & Constellations

Orion, the hunter, can be seen high in the northern sky this month. This constellation appears upside down in the Southern Hemisphere and is best recognised as the Saucepan, with Orion's belt making up the base of the saucepan and Orion's sword as the handle. Above the saucepan is the blue-white supergiant star Rigel, one of Orion’s legs, and below it is the red supergiant Betelgeuse, marking Orion’s shoulder.

The Southern Cross and the Pointers are low in the south-east which means that the Magellanic Clouds, our two nearest galaxies, are high in the sky. Away from city lights, the Magellanic Clouds can be seen as two fuzzy patches, hence their name.

International Space Station

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

6:00am – 6:06am, Friday 15th February.

The Station will appear in the north-west and travel overhead, passing by the Two Pointers, before disappearing in the south-east.

Predictions of where and when to see the ISS can be obtained from the Heavens Above website.

On This Day

1st 2003, the Space Shuttle Columbia (USA) was destroyed as it re-entered the Earth's atmosphere.

2nd 1931, the first mail delivery by rocket was made in Austria.

3rd 1966, Luna 9 (USSR) made the first softlanding on the Moon, and transmitted the first images from the Moon.

3rd 1966, the USA launched its first operational weather satellite, ESSA-1.

5th 1974, Mariner 10 (USA) returned the first close-up images of Mercury.

6th 1971, the first golf ball was hit on the Moon, Apollo 14 (USA).

7th 1984, Bruce McCandless, from Challenger (USA) made the first untethered space walk.

11th 1970, Japan became the fourth nation in space with the launch of Osumi-5.

14th 1963, Syncom 1 (USA), the first geosynchronous satellite, was launched.

15th 1564, Galileo Galilei was born.

18th 1930, Clyde Tombaugh (USA) discovered Pluto.

19th 1986, MIR (USSR), the first permanent space station, was launched.

20th 1962, Friendship 7 carries the first American astronaut into Earth orbit.

23rd 1987, SN1987A, the closest and brightest supernova since 1054 was discovered.

24th 1968, Jocelyn Bell (UK) discovered the first pulsar.

27th 1942, JS Hey (UK) discovered radio emissions coming from the Sun.