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.”
The elegant simplicity of NGC 4111, seen here in this image from the NASA/ESA Hubble Space Telescope, hides a more violent history than you might think. NGC 4111 is a lenticular, or lens-shaped, galaxy, lying about 50 million light-years from us in the constellation of Canes Venatici (The Hunting Dogs).
Somewhat appropriately spooky for Halloween in recent radar images, 600 metre-wide near-Earth object 2015 TB145 dashes by our planet today. Now believed to be a dead comet that has shed its volatiles after numerous passes around the Sun, the object makes its closest approach to Earth at 5pm GMT. UK observers with clear skies may see it with modest telescopes in the early evening.
On 14 March, the ExoMars spacecraft and Schiaparelli lander were lofted into orbit by a Proton rocket, starting a seven-month journey to the Red Planet. For the ExoMars launch, ESA’s near-Earth object (NEO) coordination centre in Italy organised a successful international campaign for ground-based optical observations of the departing spacecraft.