Make more of the season of dark skies
The new astronomy season this autumn and winter has some lovely lesser-known targets
As we move into darker skies, the winter constellations hold a treasure trove of beautiful objects. Although we are often drawn to the more familiar targets (see Old favourites, opposite), it pays to seek out some lesser-known night-sky jewels that are just as rewarding.
First, two highlights of the year. Mars reaches opposition on 13 October, when its apparent size is at its greatest. The Red Planet is visible for months after opposition, so observe it regularly to see its apparent diameter changing. Venus is blazing in the pre-dawn eastern sky during October, and on 14 October is joined by a waning crescent Moon.
Then Jupiter and Saturn will be very close together in the sky on 21 December. Found low in the western ▲ Kemble’s Cascade is a wonderful string of colourful stars, easily spotted with binoculars sky, they will easily fit within the field of view of a large telescope.
On the Moon, clair-obscur effects are some of the most intriguing phenomena to observe. One of the most well known is the Lunar X, which you can see on 22 November from 16:00 UT.
On to asterisms, and Kemble’s Cascade, in the constellation of Camelopardalis, is a chain of 15 colourful mag. +5 to +8 stars, with open cluster NGC 1502 at one end. Observe it on early evenings during November and December through binoculars or a small telescope and it will look like a vertical cascade of stars tumbling into the open cluster at the bottom.
Galaxy quest
Another lovely asterism of
40 or so mag. +5 stars is the Leaping Minnow and ‘Splash’ in Auriga. Spot them from early October, when they rise in the northeast from 19:30 UT onwards. The constellation of Auriga climbs higher in the sky over subsequent months and will be well placed throughout the winter season.
Colour contrasting double stars are beautiful, and a great example is Cor Caroli in the constellation of Canes Venatici. Well-placed in the late evening in February, it can be seen through a small scope. The primary star shines blue and, at mag. +2.9, is almost 10 times brighter than its mag. +5.6 yellow-orange companion star. At low magnifications you may also see the small barred spiral galaxy M94 nearby.
On the subject of galaxies, spring is often called ‘galaxy season’ because so many are observable at that time of year, but if you stay up until after midnight you can see many great targets from mid-December onwards. Ursa Major is home to a
lovely pair: spiral galaxy M81 (Bode’s Galaxy) and irregular galaxy M82 (the Cigar Galaxy). They easily fit into the same field of view with a small telescope and they are extremely photogenic.
Leo is teeming with galaxies and a good place to start is the Leo Triplet group of three spiral galaxies: M65, M66 and NGC 3628. These can be seen together through a small telescope, but you will need dark skies and time for your eyes to dark-adapt to see them visually. This trio is best observed when it’s more than 18° above the horizon; in mid-December that’s well after midnight. Leo will reach this altitude two hours earlier each month, so by February it is observable by 20:30 UT. Another double star, Algol, is the second brightest star in Perseus and is well placed every night during the coming months. It is an eclipsing binary system whose magnitude changes between +2.1 and +3.4 over a period of 2.87 days. Use the nearby mag. +2.1 star Gamma (g) Andromedae for comparison.
Finally, during spring, Leo plays host to minor planet 4 Vesta. It becomes an achievable binocular