Before the waxing crescent Moon of the next lunation gets too bright, Northern Hemisphere observers get the chance to track a relatively bright and recently discovered Amor-type asteroid that passes just 0.02037 astronomical units (1.893 million miles, or 7.93 lunar distances) from Earth at 15:43 UT (4:43pm BST) on Monday 29 May 2017.
Believed to be between 350 metres and 780 metres in diameter and orbiting the Sun every 4.21 years, near-Earth asteroid 2017 CS was discovered by Pan-STARRS 1 on 2 February 2017. Photometric results indicate a rotation period of about 40⅓ hours with a lightcurve amplitude of 0.18.Given its size and proximity, 2017 CS could attain magnitude +13.5 at closest approach if the predictions tabulated at the bottom of this page hold true. This means that the asteroid is a viable target for 6-inch (15-cm) and larger telescopes as it moves against the background stars at a rate equivalent to the apparent width of the full Moon every hour.Astronomical twilight now lasts all night for observers in the British Isles, except for those in the southernmost counties of England, so the darkest skies are found between midnight and 2am BST. The light of the waxing cresent Moon will also start to interfere from 31 May.
For observers in Western Europe, the following four detailed finder charts for successive nights around the time of closest approach should help you track down this fascinating small world.
Chart 1: 29 May — covering 11pm BST on 28 May to 3am BST on 29 May
Chart 2: 30 May — covering 11pm BST on 29 May to 3am BST on 30 May
Chart 3: 31 May — covering 11pm BST on 30 May to 3am BST on 31 May
Chart 4: 1 June — covering 11pm BST on 31 May to 3am BST on 1 June
Astronomers at Goldstone (and possibly Arecibo) plan to make radar observations of 2017 CS in late May that could yield a surface resolution of 3¾ metres if the signal-to-noise ratios are strong enough.
If you miss 2017 CS this time around, its next close encounter with Earth occurs on 17 May 2038 when the asteroid passes 0.0249 astronomical units, or 2.3 million miles (9.7 lunar distances) from our planet.
The Minor Planet Center classifies 2017 CS as a “Potentially Hazardous Asteroid.”
A near-Earth object (NEO) and potentially hazardous asteroid (PHA) with the catchy official name of 52768 (1998 OR2) passes just 16.4 lunar distances (6.3 million kilometres) from Earth at 09:56 UT on Wednesday, 29 April 2020. Here’s our guide to locating this fascinating asteroid in 15-cm (6-inch) aperture telescopes and smaller from the UK this month.
If you’re bemoaning the current dearth of bright planets in the evening sky, or light pollution prevents you from viewing a multitude of spring galaxies, don’t give up – there are always attractively coloured double and multiple stars to view. Join us on a tour of the Northern Hemisphere constellation of Boötes (pronounced Bo-oh-tees), the Herdsman, easily located due to its brightest star, Arcturus.
Having brushed by bright star Arcturus on 1 January, Comet Catalina (C/2013 US10) continues its trek through the constellations of the far north. Now a circumpolar object for the British Isles, in the early hours of 17 January it lies between famous double star Mizar (ζ Ursae Majoris) and the Pinwheel Galaxy (M101), virtually overhead in the UK.