One of my favorite type of astronomical events is when you get two very different types of celestial objects approach and have a close encounter in the night sky. While conjunctions, as they are known in astronomical circles, aren’t all that rare (you often get pairs of planets, or the Moon and a planet snuggle up in the sky every year), they are really cool to witness with the unaided eye and binoculars and telescopes. Over the course of next week that’s just what’s in store for early bird skywatchers as the planet Mars pays a visit to one of the most beautiful and well known star clusters called the Beehive.
Look low in the eastern sky before local dawn the last few weeks and you may have noticed a ruddy colored star halfway up the sky – that is the Red Planet. It has been slowly inching its way closer to the cluster in the constellation Cancer – the crab – culminating this last week of September. On the final morning of the month Mars will be positioned just on the upper edge of the Beehive group of stars – about 0.5 degrees or 1 full moon disk away, then on October 1st the reddish orb will actually appear nestled within the star cluster making for a really amazing site under magnification. Mars will continue its trek out of the Beehive and by October 5 it will be 1.7 degrees – or 3 full moon disks – below left of the cluster.
Known affectionately as the Beehive and more officially as M44, this deep sky object is a loose grouping of about 40 stars buzzing around together through binoculars, but really explodes into a much larger swarm of a couple hundred stars in a small telescope under low magnification. It is fairly easy to spot with the naked eye from a dark location and has been known since ancient times – Greek astronomers Hipparchos and Ptolemy, with their light pollution free skies two millennia ago observed the Beehive, calling it the ‘Little Mist’ .
The planet-cluster pairing will be a real pretty sight in binoculars and small telescopes when the two objects can be framed nicely together- making for a great photo op. Of course their proximity is just an optical illusion because while Mars is only 270 million km away from us, the cluster is over 600 light years away.
There is also a huge size difference too. Mars is 6,800 km wide, and the star cluster is nearly 23 light years across. According to a 2007 census of the cluster, there are 1010 confirmed member stars, of which 30% are probably similar to our own Sun. Could any of them have planets? Imagine how awesome the view of the cluster in their sky would be!
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.