Don’t forget to change your clocks this weekend! At 1.00 am GMT (2.00 am BST) on Sunday 25 March 2012, clocks go forward one hour as civil time changes from Coordinated Universal Time (effectively the same as Greenwich Mean Time) to British Summer Time or BST.
Unfortunately this also means that we all get a one-hour shorter weekend, but at least we get it back in October when the clocks change again.
Find out more in our British Summer Time fact file.
The vernal (spring) equinox occurred this morning at 05.14 GMT. But what actually is the vernal equinox and why does it happen?
During the course of a year the Earth completes one orbit around the Sun. From our perspective, we see this as the Sun moving through the year against the background of stars, along an imaginary line which we call the ecliptic. As the Sun moves (or appears to move) along this path, for half the year it’s seen to be above the celestial equator, which is the projection of the Earth’s equator onto the sky – this is summer in the northern hemisphere. For the other half-year it’s below this equator (northern winter).
So the Sun’s path appears to cross the celestial equator twice a year, in March and September. These times are the vernal and autumnal equinoxes – so called because at these times, day and night are of nearly equal length at all latitudes (equinox means ‘equal night’).
Find out more about equinoxes and solstices in our fact file, including why the equinoxes don’t always occur on the same day and why they don’t occur at the times when day and night are exactly equal.
See also Has spring started yet?
March has been an amazing month for planet-watching and it’s not over yet. Over the last few days we’ve had the Venus-Jupiter conjunction in the west-south-western sky. The two planets approached their closest this Tues, 13 March at just over 2 degrees apart (although still of course separated by a few hundred million miles of space).
Saturn, Mars and Mercury are also clearly visible this month. Mercury is making its best evening showing of the year, visible near the western horizon just after sunset. Mars, near its closest approach to the Earth, shines brightly in the sky all night long. And even distant Saturn is as bright as the brightest stars, visible in the south-eastern sky in the later evening.
Daytime Skywatch: Venus
Come and take a look through the Royal Observatory’s enormous 28-inch telescope at the planet Venus, as it approaches its greatest apparent distance from the Sun on 30 March.
Dates: 17, 24-25, 31 March 2012; further dates in April
Times: 16.30, 17.10, 17.50; cost :£5 | £15 family ticket
Find out more
Venus remains in an excellent position for observing for the whole of March. It then appears to gradually move closer to the Sun, heading towards the historic transit of Venus which begins on 5 June. This won’t occur again for another 105 years. Come and see our Measuring the Universe exhibition which celebrates past transits and what we’ve learnt from them.
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.