The instantly recognisable five-star M-shaped pattern of stars representing the constellation Cassiopeia (pronounced kas-ee-uh-pee-uh) lies almost overhead in the early evening as seen from the British Isles over the festive period. Cassiopeia is rich in wonderful double and multiple stars, so here’s our guide to some of the best for typical backyard telescopes.
Bright Comet 46P/Wirtanen skims past Earth just 30 lunar distances away on 16 December when it could become a diffuse magnitude +3 object almost a degree wide located between the Pleiades and Aldebaran in the constellation of Taurus. Grab your binoculars and find a dark sky location well away from streetlights to enjoy this Christmas comet before the glow from a waxing Moon gets too bright from 17 December.
If you’ve never seen a comet, there’s currently a bright example visible in the late evening about to make a close approach to the 6th brightest star in the night sky on the UK night of 2–3 September. We show you how to find Comet 21P/Giacobini-Zinner around the time it passes within a degree of prominent star Capella.
From the UK evening of Sunday, 12 August into the early hours of the following morning it’s the maximum of the annual Perseid meteor shower. This year, a new Moon setting in twilight makes prospects for watching this natural firework display particularly good. So, find somewhere away from the streetlights, settle into a garden lounger facing northeast and enjoy the show!
As darkness falls over Western Europe on the evening of 9 February, near-Earth asteroid 2018 CB lies almost overhead as seen from the UK. We show you how and when to find this 30-metre-wide space rock as it speeds through the constellations of Perseus and Triangulum, passing just one-fifth of the Moon’s distance away at 22:27 UT (10:27pm GMT).
As shooting-star devotees prepare for the naked-eye spectacle of the Geminid meteor shower in mid-December, owners of small telescopes can also witness the close passage of the meteors’ parent body — a curious “rock comet” known as 3200 Phaethon, galloping through the constellations of Auriga, Perseus, Andromeda, Pisces and Pegasus at a rate of up to 15 degrees/day.
With a waxing gibbous Moon setting at 1am BST for the UK on the night of 12-13 August, observers will have dark skies for what could be a Perseid meteor shower to remember. Some theorists believe that Jupiter’s gravitational influence has deflected more particles from parent comet 109P/Swift-Tuttle into Earth’s path for a spectacular show.
Have you ever seen Mercury with the naked eye? If not, now is the time to check the elusive innermost planet off your list. Mercury reaches greatest easterly elongation from the Sun on Monday, 18 April, the highlight of a very favourable dusk apparition in the west-northwest for observers in Western Europe and the British Isles.
A scholarly investigation of the Cairo Calendar papyrus (1244–1163 B.C.) has led researchers at the University of Helsinki to conclude that the ancient Egyptians were aware that the variable star Algol (beta Persei) had a 2.85-day period. Given that the star’s current period is 2.8673 days, this supports the theory that mass transfer between the stars of this eclipsing binary has caused a long-term increase of its orbital period.