22:00 February 2022

Summer in the Sydney region is not renowned for lots of cloudless nights. The current La Nina weather pattern is making conditions even less favourable for astronomical observing. Despite the rain being mostly a good thing – floods excepted, and we really don’t want a repeat of the devastating fires of two years ago leading into the COVID crisis – let’s hope this month gives us a few clear nights to do some observing.

A good time all year round to do some observing is 10pm. By this time in winter the night will already be several hours old; and in summer the long daylight hours have finally given way to darkness. It’s also a good time to go outside after family duties or other activities after work, with time to do a bit of observing and still get plenty of sleep ready for the next day.

If you do venture outside one night this February about 10pm, face north to see the very easy to recognise constellation Orion (The Hunter). The line of three stars making up his belt – Alnitak, Alnilam and Mintaka, run from east to west respectively pointing slightly downwards. To the upper left of the belt stars is white and bright Rigel; whilst toward the horizon to the right is the red supergiant star Betelgeuse. Across from Rigel to the right is the fainter star Saiph. To the left of Betelgeuse is Bellatrix. All of these stars make up a major part of Orion and should be bright enough to see even in light polluted suburban skies.

If you have a pair of binoculars, aim them at the three belt stars. With their extra light-gathering capacity, the binoculars reveal the three bright stars as part of a stunning field of stars lying below naked-eye visibility. Spanning between Alnilam and Mintaka is a particularly obvious S-shaped line of stars.

Staying with the binoculars, move a field upwards from Alnitak to a fainter compact line of stars signifying Orion’s sword (you may even see these naked-eye if your sky is dark enough). The middle of this group is hazy: the famed Great Nebula of Orion; also called M42 or NGC 1976. If you have a telescope, the stunning nature of the nebula is revealed. The larger the aperture of the telescope the better the view will be. This nebula is a star forming region and at its heart lie a group of four young stars called The Trapezium. These should be visible in small aperture telescopes and those of larger aperture in unpolluted skies will reveal two more fainter stars. There are many more Deep Sky Objects in the area around M42 and if you have a star atlas and the time to spend time finding them.

Another fairly easy object for even small telescopes, though, is Rigel. This is a double star with a significant brightness difference between the two components. The magnitude 7 fainter component is nearly 7 magnitudes fainter than the brighter star but with a wide separation of 10 arcseconds, a 60mm aperture telescope with decent optics will show the beautifully contrasting pair.

Using Orion’s belt stars now as a pointer, follow their line upwards and east to reach Sirius, the star with the brightest apparent magnitude as seen from Earth. Sirius is the alpha star in the constellation Canis Major (The Big Dog – mythologically one of Orion’s hunting dogs). Use binoculars to aim at Sirius, then move them upwards until Sirius is just out of the field. You should be able to see a compact group of stars. This is the open star cluster M41, or NGC 2287. (Once again, in a dark moonless sky, the haze of M41 will be visible to the naked-eye). Go to a telescope for deeper views of this rich cluster.

All of the objects described above should be visible – perhaps not if you live in a major city centre - even when the Moon is out; although the brighter the Moon the less you will see. The darkest time this month will be around February 1, when the Moon is new and not visible. First Quarter, when the Moon sets around midnight, and the week leading up to it as the phase waxes (increases), is a great time for observing the Moon itself. Full Moon, visible all night, will be on the 17th and by Last Quarter on the 24th we’ll have dark 10pm skies again until the Moon rises after midnight.

Weather permitting, then, February between dinnertime and midnight is a good time to observe a few bright Deep Sky Objects. No planets are visible at this time this month; but there is always the Moon – always worth a look.

[If you have any questions about observing feel free to send me an email: andrew@awood.com.au]