WHEN STARTING OUT IN STARGAZING, most people are particularly keen to spot the planets. The problem is, that, to the novice, planets and stars look pretty much alike. The best way to identify planets is to determine their locations in relation to nearby bright stars or the Moon, and then see how watch as they change their positions slightly as each night passes. The information below will help you spot planets using this method.
Except where indicated, all of the phenomena described here can be seen with the unaided eye. Dates and times are for the Australian Eastern Summer Time zone, and sky directions are from the point of view of an observer at mid latitudes in the Southern Hemisphere.
It is First Quarter Moon today at 6:22am Sydney time. First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.
The just-past-half Moon is the north-western sky this evening, and just above it is a group of stars called the Hyades. See if you can spot them – they’re in a triangular formation. The Hyades is an ‘open star cluster’ about 153 light years from Earth, making it the closest such cluster to our Solar System. Although you’ll probably only be able to see a handful of stars with the naked eye (assuming, of course, that you’re not standing under a streetlight), a pair of binoculars will show many more – and long-exposure photographs reveal hundreds.
Just above and to the right of the Moon is a bright orange-coloured star called Aldebaran, although astronomers classify it as a red giant. It is roughly 44 times as big as the Sun and located about 65 light-years from Earth. Think about that – if Aldebaran were at the same distance from us as the Sun, it would appear 44 times as big in the sky. Just as well it’s a long way away!
By tonight, you’ll see that Moon has moved a fair distance to the right (or east) of the Hyades, as a result of its slow orbit around the Earth. You won’t be able to miss what looks to be a bright star just below the Moon – this is the planet Jupiter. Grab a pair of binoculars and see if you can make out some tiny pinpricks of light on either side of the planet – these are the moons discovered by Galileo; Ganymede, Europa, Io and Callisto. Try to see all four – you might find there are two on each side of Jupiter, or one and three, or all four on one side – depending on where they are in their orbits around the planet. You might find that one or more are missing – this’ll be because that moon or moons is currently hidden behind Jupiter, or in the glare in front of the planet.
Today the Moon will reach the farthest point in its orbit around Earth, apogee, at a distance of 406,231 kilometres.
Full Moon occurs today at 10:53am Sydney time. If you’re out stargazing tonight and look just above (or north of) the Moon, you’ll see a bright blue star. This is Regulus, the brightest star in the constellation Leo. Located about 77.5 light years from Earth, Regulus is not one star but four, grouped into two pairs – with the naked eye we see only the brightest of the four. Multiple star systems are very common throughout the Milky Way galaxy.
Take a look around midnight tonight and you’ll see the Moon just below what appears to be a brightish red star. This is not actually a star but the planet Mars. A small planet, it doesn’t give away much detail even when viewed through a telescope.
Just below the Moon is Spica, the brightest star in the constellation Virgo. Like Regulus, Spica is a member of a multiple star system, in this case a binary (or two) star system. The two stars orbit each other so close together that not even a telescope can show them separated. In fact, so close are they that their mutual gravitational pull distorts each of them from a round shape into an egg shape. The Spica system is about 260 light years from Earth.
Tonight it’s Saturn‘s turn, with the ringed planet appearing just below and to the right of the Moon. If you have access to even a small telescope, take a look at Saturn’s amazing rings.
It is Last Quarter Moon today at 4:15am Sydney time. In the early hours of this morning you’ll find the star Antares above and to the right of the Moon. Antares is the brightest star in the constellation Scorpius. Like Mars, it is a red colour too – in fact, the name Antares means ‘rival of Mars’. Because they’re both in the same part of the sky, this is a good time to compare the two.
If you’re up before dawn, take a look out to the east and you’ll see the thin crescent Moon just above a bright ‘star’ – this is actually the planet Venus, which, aside from the Sun and the Moon, is the brightest object in the sky. Because it is in our morning sky at present, it is called the ‘morning star’. Later in the year it will be visible to west in the evening sky, and will be known as the ‘evening star’.
Today the Moon will be at the closest point in its orbit, called perigee, which is the opposite of apogee. The distance between the two bodies today will be 360,438 kilometres. If you’re up and about before dawn, and you have an unobstructed (by buildings, trees, hills etc) view of the eastern horizon, see if you can spot the planet Mercury just to right of the very thin crescent Moon. It won’t be easy to see either Mercury or the Moon, but give it a try.
Here are some more great sources of southern stargazing information:
If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!
Images courtesy IAU.
Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz
Like this story? Please share or recommend it…