31 May 2013 – Huge asteroid 1998 QE2 flies past Earth tonight. It’s also slightly surprisingly bringing its own moon with it, making it a binary asteroid. (Though that’s not as unusual as it sounds – more than 15% of large near-Earth asteroids have 1-2 moons, or companion asteroids.)

At 1.71 miles (2.75 km) wide, 1998 QE2 is large enough to create a major catastrophe if it struck the Earth – flattening everything within a 200-mile radius and releasing enough dust into the atmosphere to block out the Sun. Even its moon is 2000 feet wide, large enough to take out a city. However, neither is anything like the size of the 10 km rock that’s thought by many to have spelt the end for the dinosaurs.

Luckily though, the nearest this asteroid will get to us today is about 3.6 million miles away, at just before 10pm BST, after which it will head back out for the outer asteroid belt. Its next close approach won’t be for another two centuries, and it’s likely to miss then too.

Here are some initial NASA radar images of the asteroid and its moon.

Scientists have been waiting for this chance for a good look at 1998 QE2 since it was discovered by the Lincoln Near Earth Asteroid Research (LINEAR) program on 19 August 1998 – hence its name. (NB ‘QE2’ has nothing to do with the ocean liner, which at 294 m is only about 1/9th of the asteroid’s length.)

1998 QE2 represents one of the initial successes in NASA’s Near Earth Object Project to look for potentially dangerous large asteroids that could cause global catastrophe if they hit the Earth.

At its closest approach the asteroid will have an apparent magnitude of 11 (very faint). Amateur astronomers with computer-controlled telescopes may just be able to spot the asteroid in the southern skies. The Jet Propulsion Laboratory site has coordinates for the asteroid’s path.

7 March 2013 – Here at the Royal Observatory we’re focusing on all things alien at the moment. And this week we have a new visitor in our skies from the furthest reaches of the solar system – the unexcitingly-named C/2011 L4 (aka Comet Pan-STARRS, named for the Hawaiian telescope with which astronomers first spotted it in June 2011).

C/2011 L4 seems to be a fresh comet from the icy and distant Oort Cloud on one of its first visits to the inner solar system. It came closest to Earth a couple of days ago on 5 March, although it was still 100 million miles away, or 1.09 AU (so a little further than the Sun). It’s heading towards the Sun and will reach perihelion (closest approach to the Sun) on 10 March.

This week the comet should be visible very close to the horizon, with best visibility just after dawn. Later in March the comet will be higher in the sky (but fainter) as it heads away from the Sun. Sadly, after this we probably won’t see it again for another 110,000 years, which is thought to be the length of its orbital period around the Sun.

However, as luck would have it another and more spectacular comet, C/2012 S1 (ISON), is due to put in an appearance in November 2013 on its way towards the Sun.

13 Feb 2013 – On Friday 15 Feb, the day after Valentine’s, our planet will enjoy the astronomical equivalent of a romantic brief encounter as asteroid 2012 DA14 passes very close to Earth. ‘Very close’ in astronomical terms that is; it won’t actually get closer than 17,000 miles.

Nonetheless, that’s well within the Moon’s orbit, and nearer even than some communications satellites. It’s also the closest approach yet for a known object of this size – which is estimated at about 45-50m diameter (50-160 ft), and between 100-200k metric tons mass. The asteroid is also travelling pretty fast – thought to be over 17,000 mph (28,000 km/h).

If an object this size were on collision course with us, it would probably burst in the air about 8km above the Earth’s surface, releasing the equivalent of 2-3 megatons of TNT. That’s enough to flatten a city, though statistically of course it would be far more likely to land in the ocean.

NASA have estimated that close approaches of objects this size occur every 40 years on average. However, actual impacts of space rocks this size happen less than once every thousand years, and there are no known serious threats in the near future.

2012 DA14’s closest approach will be at about 19:24 GMT on Friday, during daylight hours for most Western Hemisphere watchers. The asteroid is too faint to be seen with the naked eye, but it will be within range for experienced amateurs with small telescopes to see it as a small fast-moving pinprick of light. For the rest of us, NASA will be live-streaming the flyby via a telescope at their Marshall Space Flight Center.

2012 DA14 is an S-type asteroid – a stony rock made mainly of silicates. It was discovered on 23 February 2012 by the OAM Observatory in La Sagra, Spain, a week after it had passed Earth at a distance of 1.6 million miles.

15 Feb update – coincidence of meteor strike in Urals

In a hard-to-believe coincidence, a meteor struck the Ural mountains area of Russia at about 9.20 local time this morning (03.20 GMT), causing injuries to over 500 people.

According to the Russian Academy of Sciences, the meteor’s estimated weight was about 10 tonnes, and it entered the atmosphere at about 33,000 mph, probably shattering at least 30km above ground and mostly burning up before impact.

8 March 2012 – No, not the long-threatened return of 70s leg-wear, though it will be received with as mixed a welcome.

The Earth’s magnetic field is currently being bombarded by the largest solar storm for the last five years, the result of two unusually large solar flares within an hour of each other around midnight on Tuesday (6 March). These generated a Coronal Mass Ejection (CME), a huge cloud of high-energy charged particles (plasma) blasted into space that reached Earth around midday today.

The resultant geomagnetic storm could affect satellites and (more positively) trigger spectacular auroral displays to the north, though effects at ground level are likely to be limited. ESA report that the storm has already affected its Venus Express spacecraft, taking out its startracker cameras.

It seems hardly any time since we were reporting the last such solar flare-triggered storm on 25 January. This is to be expected as we head towards a predicted peak in solar activity in 2013 or 2014, though the current solar cycle has been relatively quiet. That’s not to say there won’t be any large events, but it’s unlikely we’ll see anything on the scale of the great solar storm of September 1859 which shorted telegraph wires, setting off fires in Europe and North America.

Get involved – You can help spot and track solar storms at Solar Stormwatch, a joint web project of the Royal Observatory Greenwich, Zooniverse and Rutherford Appleton Laboratory. If you get involved your work will help give astronauts an early warning if dangerous solar radiation is headed their way – and you could make a new scientific discovery.