February 2018

Planets to look for

There are still no planets visible in the evening sky when the Sun sets this February, continuing an unusually long “drought” of evening planetary action. There may be some pedants out there that would say “but Uranus is there in Pisces in the north-western sky!” but regular readers of this page would know that I usually only include the five planets that don’t need a telescope to be seen. Sadly, this isn’t going to change much, and we can’t even blame February’s short length of days, either.

Jupiter is getting closer to being an evening planet, rising around midnight at the beginning of the month and then by 10pm at the end of the month. This still isn’t good for those that have to head to bed early. A Last Quarter moon will be to the left of it on the night of the 8^th.

Mars rises about an hour later. It is near Antares, the heart of the Scorpion, so if you can see two red stars in the sky, rest assured you aren’t seeing double! Saturn is up around 2am, sitting off the top of the Teapot asterism of Sagittarius. The Moon will be just below it on the morning of the 12^th.

Venus is still too close to the Sun to be seen, it won’t return to the evening sky until April, and Mercury spends most of this month and March lost in the Sun’s glare as well.

The approximate location of the three planets visible during February, Jupiter, Mars and Saturn, all in the morning sky.

Constellation of the month

Columba the Dove

Columba the Dove is a small constellation at the feet of Canis Major the Great Dog. It was originally called Columba Noachi, the “Dove of Noah” by Petrus Plancius, who introduced it to the sky in 1592. Most astronomers recognised it in their charts in the following centuries until it was formalised in the sky by the International Astronomical Union (IAU) in 1930.

The brightest star in the constellation is called Phact, which means “ring dove,” and the second brightest is called Wazn.

Columba the Dove can be found to the east of Canis Major, the Great Dog.

There isn’t much to look at in this constellation, as it lies on the edge of the star clouds of the Milky Way, so it often get forgotten, but for trivia buffs it may be interesting to contemplate that when you are looking in the direction of Columba you are also looking in the direction of the antapex; this is the direction the solar system is moving away from. While the solar system is rotating around the centre of the galaxy, taking about 225 million years to complete one orbit – this is known as a galactic year – it also bobs up and down in the galactic arm at the same time. We’re considered to be on the ‘up’ bob at the moment, heading towards a spot southwest of the bright star Vega. So looking at Columba is like looking down at our feet, looking back at where we have been.

Under the feet of Orion is the constellation of Lepus the Hare. It has two objects of interest to the small telescope owner, the first being the variable star R Leporis, also known as Hind’s Crimson Star for its notably red colour at maximum. It last reached maximum in early December 2017 and is now fading, but may still be within reach.

More reliably found is the globular cluster Messier 79. If you draw a line through the stars alpha and beta Leporis and continue it on you should find this moderately distant globular cluster that lies around 42,000 light years away. It has a lot of older, redder stars in it, as is common for globular clusters, but its particular make-up has some astronomers believing it may actually belong to another galaxy that is passing close to the Milky Way at the moment, known as the Canis Major Dwarf Galaxy. Whether it is or not, it will still be visible all summer for you to enjoy in the sky.

Lepus the Hare is at the foot of Orion the Hunter. The bright stars Rigel and Saiph mark his knees.

More Proper Names for Bright Stars Announced

Just before Christmas last year the International Astronomical Union (IAU) announced it had added 86 more proper names to its list of star names. Some were historic, such as Barnard’s Star, a small nearby star that has the fastest known proper motion in the sky, but most of them were cultural names from non-western societies. These included four star names from Australian Aboriginal culture.

The one that has garnered the most attention is Ginan (pronounced “ghee-nun”, with a hard “G”), being attached to epsilon Crucis, the fifth brightest star in the Southern Cross. To the Wardaman people of the Northern Territory it represents a red dilly-bag filled with special songs of knowledge. The star is orange-red in colour, a testament to the Wardaman people’s skill in observing the sky.

The stars of the Sothern Cross that have been assigned proper names to date: Alpha Crucis = Acrux, beta Crucis = Mimosa, gamma Crucis = Gacrux and epsilon Crucis = Ginan. Only delta Crucis is yet to be assigned a name.

When these new names were announced, some people mistakenly thought the whole of the Southern Cross was being renamed, but this is not the case. The star can still be called epsilon Crucis, if you wish, or you can call it both! And it will have a plethora of catalogue numbers assigned to it, such as HD 107446, HIP 60260 and SAO 251862. They are all correct. Some of the other stars were assigns proper names earlier; only delta Crucis is yet to be assigned a proper name.

If you would like to read more about the four aboriginal names that were chosen in the latest list and the stories behind them you can go to researcher Duane Hamacher’s article where he recounts them and shows how to find them in the sky. I will endeavour to include these new names in the constellations of the month as we encounter them during our progress through the year.