It would seem that near-Earth asteroids are rather like buses: you can wait ages for one, then two come along in quick succession. Shortly after I told you about 2015 FP118, news broke of the first observations of 2018 RC at ATLAS-MLO Hawaii on 3 September 2018.
Believed to be up to 70 metres in size – the same as the wingspan of a Boeing 747 Jumbo Jet – Aten-type asteroid 2018 RC has a 289¾-day orbit that brings it to within 0.653 astronomical unit (AU) of the Sun at perihelion, out to 1.061 AU at aphelion.
Earth has a very close encounter with 2018 RC at 12:09 TDB (1:08pm BST) on Sunday, 9 September 2018, the asteroid passing just 218,300 kilometres from the surface of our planet, or slightly less than 60 percent of the Moon’s average distance.
Observing 2018 RC from the UK on the night of 8–9 September
Despite the asteroid’s relatively small size, its proximity to Earth this weekend means that it could attain magnitude +12.1, making it a viable target for 6-inch (15-cm) aperture and larger backyard telescopes. Saturday night to Sunday morning in the UK finds the asteroid in southern Aquarius, some 9 degrees north of first-magnitude star Fomalhaut in the constellation of Piscis Austrinus, the Southern Fish.
The UK observing window for viewing 2018 RC at its brightest lasts from approximately 10pm BST on Saturday, 8 September to 3am BST the following morning. The asteroid is best seen highest in the southern sky of the British Isles around 1am BST on 9 September when it’s moving against the background stars of Aquarius at a rate equivalent to the width of the full Moon every 12 minutes.Finding 2018 RC the easy way
Observers with computerised GoTo mounts or digital setting circles may prefer to locate the asteroid from the half-hourly topocentric ephemeris computed for the centre of the British Isles found at the bottom of the page.
See asteroid 2018 RC live online
If you are clouded out or don’t have a telescope large enough to see or image it, then why not follow this fascinating NEO online? The Virtual Telescope Project 2.0 is hosting a live event starting at 22:00 UTC (11pm BST) on Saturday, 8 September.