Observer’s Guide – March 2015
Urban Astronomer has been running for almost five years, and yet we’ve never published a guide to what you can expect to see in the sky. Shocking. So starting today, we’ll be posting a monthly guide to things worth looking for, with a bias towards the view from the Southern Hemisphere (because that’s where I live).
This month is dominated by close encounters and conjunctions. First, on the 2nd and 3rd day of the month, the Moon will be passing close by Jupiter and M44 (the Beehive Cluster). M44, known to the ancients as a fuzzy blob called Praesepe, is an open cluster of young stars who’ve recently escaped their nursery, but haven’t yet gone their separate ways. Seen through binoculars, it has a shape similar to a natural bee-hive, and is a popular example of an open cluster. You’ll need those binoculars to find it, though, because the bright light of the almost-full Moon will make it hard to see otherwise.
Shortly afterwards, on the 4th, Venus will be passing very close by Uranus. At their closest, they’ll be less than 0.1° part, or about a third of the diameter of the full Moon. Now Venus is impossible to miss, but Uranus is too faint to see with the naked eye, so you’ll definitely need binoculars or a telescope to see them together. This could be quite challenging to see, since Venus sets shortly after the Sun, so you’re trying to spot a faint object through the glow of twilight. If you don’t manage to spot them, as a consolation you can see Mars instead, a few degrees below and to the left of Venus.
The following day, on the 5th, the Moon will be full, but this particular full Moon will be the smallest of the year – a MiniMoon. You’re welcome to try and spot the difference in size, but full Moon’s are hard to compare because they only come once every 29 days. The difference between a Super and Mini Moon is real, but only really visible if you can put them next to each other. If you have a camera with a long enough zoom lens, then you could take pictures of these events and compare them, but it’s not really possible to compare one view by eye with another view several months away.
On the 11th, it will be Mars’s turn to pass by Uranus. It won’t be as close as the Venus encounter, but still less than half a full Moon diameter. This event will be even harder to see than the Venus encounter, though, since both planets will be very low on the horizon and set while twilight is still fairly bright. I’d encourage you to go for it, but it will be a challenge.
Back to the Moon, on the 12th and 13th it will be passing close by Antares and Saturn, both in the constellation Scorpius. The three objects will form a nice triangle, made more interesting by Saturn being about a half a degree from the star Nu Scorpii, near the head of the scorpion. Unfortunately, Scorpius only rises at around midnight, so you’ll need to be up in the early hours of the morning to see it.
On the 19th, if you get up before the Sun rises, you can catch a spectacular sight: The almost-new Moon forming a crescent to slender that you could easily miss it, only 3.5° fro Mercury. If you have a clear view of the Eastern horizon, look that way about a half hour before the Sun rises and find Mercury – it will appear as a bright star, twinkling like mad because it’s so low in the sky. The Moon itself will be only 2% illuminated, so this is actually quite a challenging event to see. It might be worth trying to photograph it with a medium zoom telephoto lens, since such a thin crescent is very hard to find with the naked eye, because it’s dark and the sky will already be brightening before sunrise.
The least interesting event of the month, but most important, is the equinox on 20 March at 16h57UT (that’s 6:57pm South African time). It marks the change of seasons from Summer to Autumn for us in the South, and Winter to Spring for those in the North. Nothing obviously changes, apart from this being one of the two days in the year when daytime and night-time both last almost exactly twelve hours.
Then on the 20th we have a close encounter between the Moon and Venus. This will play out almost exactly like the Mercury event two days earlier, except that the Moon’s crescent wil be a little thicker and therefore easier to see, and it will be visible just after sunset, instead of before sunrise.
Finally, two days later on the 22nd, the Moon will passing between the two most famous open clusters in the sky, the Pleiades and the Hyades, both in Taurus. The Pleiades are commonly known as the Seven Sisters and make a tiny kite-shaped grouping a little larger than the full Moon, while the Hyades are a much larger V-shaped group that make up the head of the bull Taurus.
And that’s it for the month of March! If you’d like to report back on your view of any of these events, tell us about it in the comments below!
Source: Universe Today and the Astronomical Society of South Africa’s annual Sky Guide.