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…
27 January – A small asteroid will pass within about 60,000km (roughly 37,000miles) of the Earth this afternoon, reaching its closest at about 16.00 GMT. This is one of the closest asteroid approaches ever recorded, but it poses no threat to Earth or to our geostationary satellites (which orbit at a distance of around 20,000km).
The asteroid has been named 2012 BX34 and is estimated to be about 11m (36ft) in diameter. Though it won’t be visible to the naked eye, keen amateur astronomers still have a good chance of sighting it.
Fortunately it’s very rare for large asteroids to strike the Earth – perhaps 60 objects greater than 5 km across have done so in the last 600 million years (or an average of about one every 10 million years). One of the most famous was of course the 10km-wide asteroid that may have led to the extinction of the dinosaurs 65 million years ago.
Smaller objects hit our planet more frequently – about 500 football-sized rocks strike the Earth each year.
Find out more about asteroids:
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 Royal Observatory, Greenwich is famously the home of the Prime Meridian of the World (0° Longitude) where each day and year officially begins, and of Greenwich Mean Time (GMT), as well as of the celebrated Harrison timekeepers.
Now the Royal Observatory is also home to OMEGA‘s London 2012 Countdown Clock. Installed on the Prime Meridian Line by OMEGA, the Official Timekeeper of the Games, the clock will tick away the seconds, minutes, hours and days until the start of the London 2012 Olympic Games – some of which will be hosted in Greenwich Park.
The clock was unveiled yesterday (27 July 2011) in time to celebrate ‘One Year to Go’ to the start of the Games.
21 December 2010 – UK viewers will be able to catch the start of a total lunar eclipse this morning, the first for three years, with totality starting at 07.41 GMT and lasting a little over an hour. Within the UK, Scotland and Northern Ireland will get the best views.
Lunar eclipses occur when the Moon passes through the Earth’s shadow. During eclipse, the Moon may turn blood red or pink, with indirect sunlight giving the Moon a ghostly hue. Find out more in our eclipses fact file.
The last time a total lunar eclipse occurred on the winter solstice was in 1638, and the next time will be in 2094.
For the first time scientists have used data analysed by the public to make a real-time prediction of a significant solar storm that should hit Earth on Monday 13 December, thanks to the Solar Stormwatch web project.
The initiative, launched in February by the Royal Observatory, Greenwich (ROG), in partnership with the STFC Rutherford Appleton Laboratory and the Zooniverse Citizen Science Project, makes it possible for anyone with internet access to get involved in the latest solar research by helping to spot and track storms as they erupt from the Sun. These collective measurements enable scientists to forecast the arrival of storms far enough in advance to issue effective pre-emptive warnings for the first time.
Solar storms, power grids and aurora
The Sun is much more dynamic than it appears to the naked eye. Intense magnetic fields churn and pummel the Sun’s atmosphere, storing enormous amounts of energy that, when released, can hurl billions of tons of material out into space in eruptions called Coronal Mass Ejections (CMEs) – or solar storms.
The latest storm identified by the project is predicted to hit Earth at 07.32 GMT on Monday 13 December. Solar storms have the potential to interfere with communication satellites, upset GPS navigation systems and also pose a health risk to astronauts on the International Space Station. In severe cases they can even knock out entire power grids causing widespread disruption here on Earth.
On a gentler note, the particles making up a solar storm can produce beautiful displays of the Northern and Southern Lights as they collide with the Earth’s upper atmosphere. Scientists are not overly concerned about the effects of the current storm, but the early warning provided by Solar Stormwatch will allow precautionary measures to be put in place.
Predicting storms
In the past solar scientists were only certain an approaching storm was directed towards Earth a few hours ahead of impact, but data from the NASA STEREO mission used by the Solar Stormwatch project allows Earth-directed storms to be identified up to three days in advance, enabling space agencies and power companies to take steps to limit any damage. In order to identify hazardous solar activity, the solar wind needs to be monitored constantly – a task that is too much for scientists to deal with on their own – so the Solar Stormwatch website utilises the spotting skills of the public to alert them to incoming storms.
Dr Marek Kukula, Public Astronomer at the ROG, says, ‘Solar Stormwatch is special in that it harnesses public interest in astronomy to provide data that is invaluable to scientists. The more people that take part in “stormwatching” the more we will learn, and the fact that the volunteers’ work has now enabled us to predict when a storm will hit the Earth is a significant milestone, not just for the project, but for science as a whole’.
Solar Stormwatch is the latest chapter in a long history of solar research at the Royal Observatory, Greenwich, dating back to the 1870s when the Observatory housed a photoheliograph – a telescope that took daily photos of the Sun to track sunspots. Visitors to the Royal Observatory today can see this telescope housed in the Altazimuth Pavilion.
Take part
Join the hunt for solar storms at the Solar Stormwatch website. Help scientists spot explosions on the Sun and track them across space to Earth.
Image: Composite image of a coronal mass ejection taken by the SOHO spacecraft, 2002 © SOHO, NASA and ESA
Three recent discoveries with implications for the search for other Earth-like planets and for life in the Universe.
Red dwarfs increase possibility of other Earths
The universe may contain three times more stars than has been previously thought. New observations using the Keck telescope in Hawaii showed that galaxies older than ours may contain 20 times as many red dwarfs, which are older and less bright than the Sun.
This also greatly increases the estimated number of planets in the universe and therefore the likelihood of other ‘Earth-like’ worlds. Red dwarfs tend to be at least 10 billion years old, allowing plenty of time for complex life to evolve on planets in their system.
The discovery, led by a team from Yale University, also reduces the amount of ‘dark matter’ needed to explain the ‘missing mass’ of the universe.
First known atmosphere round ‘Super-Earth’ exoplanet measured
Scientists at the Harvard-Smithsonian University Centre for Astrophysics have been able to measure the atmosphere of a ‘Super-Earth’ exoplanet for the first time. The planet – GJ1214b – is 40 light years distant, is about three times the size of Earth and seven times the mass, and is the first of its kind around which an atmosphere has been detected. Measurements using the ‘transit method’ seem to show that it does not have a hydrogen or helium atmosphere, but further work will be needed to determine whether it has a thinner and steamier atmosphere or a thicker, cloudier one.
See related post New exoplanet may be habitable (1 Oct 2010)
‘Extremophile’ bacteria break the mould for life
Up till now, it’s been thought that all life on Earth must contain the six elements carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus. But an Arizona State University and NASA team have found a bacterium in a California lake that is able to substitute the usually-poisonous element arsenic for phosphorus.
The discovery of a separate ‘tree of life’ would have major implications in the hunt for alien life in the Universe. However, the researchers found that the bacterium still thrives best in a phosphorus environment, meaning that it is probably simply an unusual branch of the known tree of life rather than a member of an entirely different one.
26 November 2010 – NASA’s Cassini probe has scooped oxygen from the atmosphere of Saturn’s second largest moon, the icy Rhea. This is the first time the gas has been directly seen in the atmosphere of another world, though scientists have previously used telescopes to detect oxygen on other moons and planets, including Jupiter’s moons Europa and Ganymede.
In a flyby in March, Cassini’s instruments found an extremely thin atmosphere – or strictly exosphere – with tiny concentrations of oxygen and carbon dioxide. At a peak density of around 20 billion molecules per cubic metre, the density of oxygen in Rhea’s exosphere is about 5 million million times lower than that found in Earth’s atmosphere.
Rhea’s exosphere is maintained by a constant stream of high-energy particles bombarding the moon’s icy surface, breaking water molecules and forming oxygen. The carbon dioxide may also be produced by particle impacts, or could come from dry ice trapped within the moon or from carbon-rich meteor deposits.
Team leader Dr Ben Teolis believes that there could be billions of similar exospheres throughout the galaxy. One strong candidate is Saturn’s moons Tethys, which Cassini is due to fly by in December 2011.
The Cassini mission is a joint project of NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI). Cassini arrived at Saturn in 2004 after a seven-year voyage across billions of kilometres of space, and its mission has been extended until 2017 when it will destroy itself by plunging into Saturn’s atmosphere.
See a selection of beautiful images from the Cassini-Huygens mission in our Visions of Saturn pages.
19 Novmber 2010 – Over the past 15 years scientists have found nearly 500 planets outside our solar system, but till now all of these have been within our galaxy – the sheer distances involved preclude detection of planets outside the Milky Way. But now astronomers have identified a planet orbiting a star that originally belonged to a separate dwarf galaxy, one which was swallowed up by the Milky Way some 6 to 9 billion years ago.
The new-found planet HIP13044b is about 2000 light years from Earth, is at least 1.25 times more massive than Jupiter, and orbits close to its star with an orbital period (year) of just 16.2 days. Researchers say the planet would have been formed in its solar system’s early days, prior to incorporation into the Milky Way.
The planet’s star HIP13044 (appearing in the southern constellation Fornax) has passed its red giant phase and is nearing the end of its life, so it offers an intriguing glimpse into what the last years of our own Solar System may look like. The star is rotating relatively fast, which may be a result of swallowing its nearest planets during the red giant phase. One remaining puzzle is that the star does not appear to contain the heavy elements which are usually thought to be needed for planet formation.
Researchers discovered the planet using the ‘radial velocity method’, using a telescope-connected spectrograph at the ESO’s La Silla facility to detect the small wobbles in a star caused by an orbiting planet’s gravitational pull.