Make the most of any clear skies near the end of the first week of this month as you don’t want to miss 2017 VR₁₂, a space rock the size of The Shard in London that hurtles past our planet less than four lunar distances away on 7 March. Predicted to exceed magnitude +12 at its closest, this near-Earth asteroid is a viable target for 4-inch (10-cm) aperture telescopes and larger as it rapidly heads south through the constellations of Coma Berenices and Virgo.

Discovered by Pan-STARRS 1 in Hawaii on 10 November 2017, 2017 VR₁₂ is an Apollo-type asteroid that orbits the Sun once every 585½ days. Studies indicate that its size lies between 220 and 490 metres, rotating once on its axis every 1.4 hours with an amplitude of 0.2 magnitudes.

At 07:53 UT (7:53am GMT) on 7 March, 2017 VR₁₂ passes Earth at a distance of 1.44 million kilometres (897 thousand miles), or 3.76 times the distance of the Moon. Although classified as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center, there is no possibility that 2017 VR₁₂ will collide with Earth this time around – its closest approach to our planet for at least the next 177 years.

Observing highlights for 2017 VR₁₂
As darkness descends in Western Europe on 5 March, the asteroid lies in the constellation of Canes Venatici, crossing the border into Coma Berenices shortly after 20:30 UT. At 1:40am GMT on 6 March, 2017 VR₁₂ passes just 0.9 degrees west of magnitude +4.2 beta (β) Comae Berenices, the star and asteroid visible in the same field of view of telescopes magnifying 30× or less. At this time, 2017 VR₁₂ is a magnitude +12.1 object travelling at a rate of 0.7 degrees/hour against the background stars, or the equivalent of Jupiter’s angular diameter every minute.

Observers situated in East Asia have a visual and astrophotographic treat in store as 2017 VR₁₂ clips the edge of magnitude +7.7 globular cluster Messier 53 in Coma Berenices close to 13:50 UT on 6 March. Sadly for observers in Western Europe, this occurs in daylight. At UK dusk on 6 March, 2017 VR₁₂‘s rapid southerly motion carries it over the constellation border into Virgo.

Shortly after 4:30am GMT on 7 March, the magnitude +11.8 asteroid passes half a degree east of magnitude +4.8 star sigma (σ) Virginis. At this time, 2017 VR₁₂ and σ Virginis lie within the same field of telescopes magnifying up to around 70×, the asteroid’s motion relative to the background stars being 0.9 degrees/hour, or the angular diameter of Jupiter every 50 seconds.

As night falls in the British Isles on the evening of 7 March, observers can prepare for the highlight of 2017 VR₁₂‘s close flyby – its near brush with Virgo’s brightest star, first-magnitude Spica. At closest approach, the asteroid passes just 0.8 degrees east of Spica at 11:30pm GMT. At this time, if you have a 4-inch (10-cm) or larger telescope with Spica centred in an eyepiece magnifying around 30×, you have an excellent chance of seeing the real-time motion of 2017 VR₁₂ if its predicted magnitude of +12 holds true.

Viewing 2017 VR₁₂ online
If you don’t own a telescope, or it’s cloudy where you live, then why not watch 2017 VR₁₂ online? The Virtual Telescope Project and Tenagra Observatories, ltd. are providing two opportunities to see near real-time images of the asteroid accompanied by commentary from scientific staff on Wednesday, 7 March. The first live broadcast from Ceccano, Italy starts at 00:00 UT (12am GMT), while the second live broadcast from Arizona, USA starts at 10:00 UT (10am GMT). To find out more, follow this link.