The annual Lyrid meteor shower is currently underway, due to peak in the early morning hours of Sunday 22 April. This year the absence of moonlight should help with viewing, but unfortunately the forecast of cloudy skies across most of the UK may cancel that out.

The Lyrids are a reliable (if generally unspectacular) annual shower of bright fast meteors associated with the periodic Comet Thatcher. The shower gets its name from the constellation Lyra in the north-eastern sky (as seen from the UK), as this is the part of the sky from which the meteor trails appear to radiate.

Most Lyrid meteors are around magnitude +2 but some, known as ‘Lyrid fireballs’, are much brighter and cast shadows for an instant, leaving behind smoky trails of debris that can last several minutes.

The Lyrids usually only produce between 5-20 meteors per hour, but occasionally the Earth passes through a thicker part of the comet’s dust stream resulting in a more intense shower. In 1982 amateur astronomers counted 90 Lyrid meteors per hour, and in 1803 an even stronger ‘storm’  was observed.

The Lyrids were observed as far back as 687 BC, as recorded in the Chinese ‘Zuo Zhuan’ or Chronicle of Zuo, making them the earliest-known meteor shower.

The next major annual meteor shower is the Eta Aquarids, a light shower associated with Comet Halley and due to peak around 5 May.

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.

29 February 2012 – Happy Leap Day to all our readers, and Happy Birthday to all ‘Leaplings’!

Leap years are a way of making the calendar year match the Earth’s actual or astronomical year – i.e. the length of our orbit around the Sun, which is 365.24237 days. The 365-day Gregorian calendar is therefore just under a quarter of a day shorter than the astronomical year (technically the vernal tropical year), so the introduction of an extra day (almost) every fourth year pretty much resolves the problem.

The rule is that a year is a leap year if it’s divisible by 4, apart from years ending in 00 (except those divisible by 400, e.g. the year 2000, which are leap years).

The net effect is to make the average length of the calendar year 365.2425 days. The difference between this and the true length amounts to about 3 days in 10,000 years.

The first leap year in the modern sense was 1752, when 11 days were ‘lost’ from the month September with the adoption of the Gregorian calendar by Britain and her colonies. After 1752 we adopted the system that’s still in use today.

Find out more in our fact file…

Solar flare seen by ESA/NASA SOHO satellite
on 23 January,
shortly after a large solar flare
occurred at 03:59 GMT. Credits: ESA/NASA

25 January 2012 – A stronger-than-average solar flare at 03:59 GMT on Monday set off a coronal mass ejection travelling at 1400 km/s and reaching Earth yesterday afternoon. Its effects are likely to continue throughout today (Wednesday 25 Jan).

Solar flares are enormous explosions caused by the sudden release of energy from the magnetic fields of sunspots – temporary areas of intense magnetic activity in the Sun’s atmosphere (corona). Solar flares in turn can result in coronal mass ejections (CMEs) – huge clouds of high-energy particles blasted into space by a solar flare. These clouds of material can strike the Earth
causing geomagnetic storms and triggering a range of phenomena. Some of these are beautiful like the aurora, but others can be disastrous – disrupting satellites and communications systems.

Monday’s solar flare triggered the strongest stream of protons seen since 2005. However, scientists predict that the current CME will only cause a minor geomagnetic storm without any visible effects on the ground nor any serious effects on satellites, phone networks or power grids.

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.

The Astronomy Photographer of the Year competition is back! Now in its fourth year, the competition continues to showcase incredible images from amateur astrophotographers all around the world, featuring beautiful objects from within our solar system and far into deep space.

Anyone can enter – whether you’re new to astrophotography or a seasoned amateur, and whatever your age. We’ve had a huge range of images in previous years, from amazing landscape photography that captures the Moon and the Sun to stunning deep space images taken by robotic telescopes. Find out how to enter and what you could win.

Overall winner 2011: Jupiter with lo and Ganymede,
September 2010 by Damian Peach (UK)

To enter the competition you will first need to add your photos to the Astronomy Photographer of the Year group on the photo-sharing website Flickr. Once you have done this, please fill in the relevant online application form on the Astronomy Photographer of the Year website.

The four main competition categories are Earth and Space, Our Solar System, Deep Space and Young Astronomy Photographer of the Year. The judges will also be awarding three additional special prizes: People and Space, Best Newcomer, and Robotic Scope Image of the Year. Find out more about the categories and prizes.

Entries to the competition close at midday (BST) on Friday 29 June 2012.

The winning images will be displayed at the Royal Observatory Greenwich from September in the free Astronomy Photographer of the Year exhibition. There’s still time to see the winning images from 2011 (closes 12 February).

Good luck, and we look forward to seeing your photos in Astronomy Photographer of the Year 2012!

The first meteor shower of the year is underway and peaking at the moment. The Quadrantids is one of the most spectacular but brief showers of the year, at its peak producing 60-120 meteors per hour.

Meteors, popularly known as ‘shooting stars’, appear as fleeting streaks of light and most are caused by particles no bigger than grains of sand. These collide with the Earth’s atmosphere at up to 70 km per second (157,000 mph) and burn up. With patience, meteors can be seen on any night of the year.

The Quadrantids

All the meteors in the Quatrandid shower appear to come from the same point in the sky, or radiant, situated near the familiar grouping of the Plough. The shower is named for the former constellation Quadrans Muralis, the stars of which once lay in that direction. The Quadrantids are less well-known than many other meteor showers, probably because only the hardiest observers brave the cold January nights.

In contrast with many meteor showers, the Quadrantids are not obviously connected to a particular modern-day comet but some astronomers believe them to originate from a large cometary body that broke up thousands of years ago.

In 2003, SETI institute astronomer Peter Jenniskens suggested that the Quadrantids are tied to the near-Earth asteroid 2003EH1 (see Dr Jenniskens’ paper here). Dr Jenniskens believes this object is actually an extinct comet, possibly once seen by the Chinese 500 years ago in 1490. The comet may have subsequently broken up, releasing all its volatile material in a single event. When the Earth passes through the dust cloud each January we see the meteor shower.

Viewing meteors

Unlike many astronomical objects, observers need no special equipment to view meteors. The sensitivity and wide field of view of the human eye are perfect for watching the Quadrantids and all observers need to do is watch the sky for a few minutes. 

As ever, it pays to leave the lights of the city behind and rural sites will offer the best view of the Quadrantids, but (weather permitting) they should be clearly visible all over the UK. 

The next major meteor shower of the year will be the Lyrids, which peak around 22 April. Find out more about annual meteor showers in our fact file.

Image: Meteors in the Quadrantid shower in January 1995. The image superimposed many video frames to illustrate the apparent origin of the meteors from their radiant. Credit: Sirko Molau, IMO, Archenhold-Sternwarte, NASA.

*Times are BST not GMT, and may not correspond exactly with the official (religious) sighting of the crescent moon.

The dates of Ramadan and other Islamic months depend on the sighting of the new crescent Moon.

Information on the visibility of the Moon from anywhere in the world is available from HM Nautical Almanac Office’s Websurf facilty:

• - accept the conditions of use (Websurf homepage)
• - select the ‘Moon-Viz’ link
• - choose or search for a place
• - select a date range
• - The visibility information (time) is in the ‘BEST TIME’ column;
  Moon set time is in the ‘Moon set’ column. NB add +1 hour for BST.
   

Also of interest

• - Al Hijra and the Islamic Calendar – fact file
• - Persian astrolabe – a beautiful astrolabe dating from 1070AH by the Islamic calendar, and including a grid for finding the direction of Mecca from a number of different towns and cities.
• - Arabic (Islamic) brass globe – 18th-century globe showing all 48 constellations that were known to the Ancient Greeks, and engraved with the Arabic names of some of the stars.
• - Transmission of knowledge – as Islam spread across Northern Africa from the 7th century, it helped change the purpose of astronomy: for example, it was now needed to produce accurate tables of prayer times.