Discovered by the Catalina Sky Survey on 4 February, Apollo-class asteroid 2018 CB is believed to be 20 to 40 metres in size and orbits the Sun once every 611 days. This space rock flies past Earth at a distance less than one-fifth that of the Moon at 22:27 UT (10:27pm GMT) on 9 February. As darkness falls in Western Europe this night, 2018 CB passes almost overhead as seen from the UK, dashing through the constellations of Perseus and Triangulum at rates exceeding 20 degrees/hour. Click the graphic for a 45-degree-wide scaleable PDF chart suitable for printing showing field stars to magnitude +8 and the asteroid’s track as seen from the heart of the British Isles. At its brightest, 2018 CB should be visible in 8-inch (20-cm) ‘scopes and larger. AN graphic by Ade Ashford.You could be forgiven for thinking that we’re currently in the midst of a swarm of near-Earth asteroids. Since the start of this year, at least a dozen of these space rocks have already whizzed by our planet closer than the Moon. That’s in our backyard astronomically speaking, but not near enough to get worried about. None of these newly-discovered objects poses an immediate threat to Earth, their large number and frequency merely the result of better detection methods.
But if you wish to see a particularly close approach from one of these asteroids, you only have to wait until Friday, 9 February at 22:27 UT (10:27pm GMT) when 2018 CB passes just 0.000466 astronomical units from Earth, or slightly less than one-fifth of the Moon’s distance – that’s a mere 69,700 kilometres (43,300 miles), or twice the distance of our belt of geosynchronous communication satellites.
Apollo-class asteroid 2018 CB was only discovered by the Catalina Sky Survey on 4 February. Believed to be 20 to 40 metres in size, it orbits the Sun every 611 days. Looking ahead somewhat, this asteroid passes even closer to the Moon (0.000196 astronomical units, or 29,400 kilometres) at 3h UT on 8 February 2090.
Observing highlights for the UK on 9 February
At 19:12 UT (7:12pm GMT), the asteroid passes just 15 arcminutes (one-quarter degree) southeast of magnitude +3 double star delta (δ) Persei when 2018 CB is moving against the background stars at a rate equivalent to the width of a full Moon every three minutes. At this time the star and asteroid are virtually overhead as darkness falls as seen from the heart of the British Isles. If you have an 8-inch (20-cm) or larger telescope with δ Persei centred in an eyepiece magnifying 50x or less between 7:10 and 7:15pm GMT, you’re likely to see 2018 CB’s motion realtime if the predicted magnitude of +12.7 holds true.At 20:10 UT (8:10pm GMT), 2018 CB passes 1⅔ degrees southeast of open cluster Messier 34 when the asteroid’s motion against the background stars of Perseus has increased to the apparent width of a full Moon every two minutes. One hour later, 2018 CB passes 1.9 degrees southeast of Local Group galaxy Messier 33 and the asteroid’s motion against the background stars of Triangulum has increased to a whopping 20 degrees/hour, or the width of a full Moon every 1½ minutes. Click the graphic for a 45-degree-wide scaleable PDF chart for UK-based observers showing field stars to magnitude +8. AN graphic by Ade Ashford.At 20:10 UT (8:10pm GMT), 2018 CB passes 1⅔ degrees southeast of open cluster Messier 34 when the apparent motion of the asteroid against the background stars of Perseus has increased to almost 15 degrees/hour, or the apparent width of a full Moon every two minutes!
Shortly before 8:35pm GMT finds 2018 CB crossing the constellation border into Triangulum where the asteroid passes ⅓ degree northwest of magnitude +3 binary star beta (β) Trianguli at 20:45 UT (8:45pm GMT). If the magnitude predictions hold true, this is another opportunity to see a conspicuous star and 2018 CB in the same field of view of 8-inch telescopes and larger at a magnification around 100x.
Finally, 2018 CB passes 1.9 degrees southeast of magnitude +5.7 Local Group galaxy Messier 33 at 9:12pm GMT (21:12 UT). By this time the asteroid’s motion against the background stars of Triangulum has increased to a whopping 20 degrees/hour, a rate equivalent to the width of a full Moon every 1½ minutes.The table above shows the position of asteroid 2018 CB every ten minutes for the interval that it is brightest and visible from Western Europe. Universal Time (UT) is used, equivalent (for our purposes) to Greenwich Mean Time (GMT). Topocentric central UK equatorial coordinates are for the current epoch (J2018.1) for direct entry into digital setting circles or GoTo mount hand controllers. The asteroid’s predicted visual magnitude (Mag.) and distance in astronomical units (Delta) is also shown. Data credit: Minor Planet Center / NASA HORIZONS / Ade Ashford.
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.
Five hundred-metre-wide asteroid 2017 CS passes just 1.9 million miles, or 7.9 lunar distances, from Earth on the afternoon of Monday 29 May 2017. For a few nights around this date, Northern Hemisphere observers with 6-inch and larger ‘scopes can see the asteroid gallop through the constellations of Canes Venatici, Boötes and Hercules at up to 14 degrees/day.
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