Scanning the skies for shooting stars
Last year, the Natural History Museum switched on a CCTV camera with a difference - instead of filming people, this one records the night sky.
Installed in December 2015, the camera is part of a network of detectors taking still images and videos of meteor activity in the skies above the UK.
Monitoring meteors from different locations on the ground can tell us about the size of objects, the orbits they're following, and even where in space they came from. Museum scientist Ashley King, who is overseeing the project, explains its importance.
Flashes and showers
On a clear night you may have seen a bright light streak across the dark sky - or what’s commonly known as a shooting star.
However, this isn't actually a star at all. It's space debris such as dust, ice or rock entering Earth's atmosphere at speeds of up to 160,000mph, generating light and heat. The flash of light is what we refer to as a meteor, while the material itself is a part of a meteoroid.
'It is estimated that up to 200 tonnes of extraterrestrial material enters Earth’s atmosphere every day,' says King. 'But as the majority of it is made up of tiny specks measuring only a few millimetres on average, most of it vaporises before reaching Earth's surface.'
When many meteors are seen at the same time, this is known as a meteor shower. Showers result when comets - large icy, bodies made up of rock or metals - travel into the warmer, inner regions of our solar system and break up.
As the comet heats up, thousands of particles of rock and dust are released. And if Earth's orbit intersects this trail of debris, we see a meteor shower.
Comets tend to have regular orbits, so scientists can predict when they are going to cross Earth's path and where to look in the night sky. That's how we know to stargaze in mid-August to watch the Perseids, and in mid-April to watch the Lyrids.
CCTV contributing to science
The Museum has a world-class collection of meteorites - rocks from space that make it through Earth's atmosphere and land on the surface. Each meteorite records valuable details of the early solar system.
But unless their fall is recorded, it's difficult to know which part of the solar system they came from.
'Knowing where meteorites originated is important for understanding the chemical characteristics of the different regions and bodies in the solar system,' says King.
'If the meteor event - the activity in the sky preceding a meteorite fall - is recorded from at least two different locations, that's helpful. It lets us estimate the orbit and origin of that meteorite, so we can figure out where in the solar system it came from.'
The Museum's meteor detector is nothing fancier than a CCTV camera. It is switched on by timer every evening, running through the night until around 5.00. It functions on the same principles as a camera trap, responding to both brightness and movement.
King downloads the data once a week. 'We've captured several interesting pictures, but because of cloud cover or light pollution, most of the time there's not much there.'
As well as capturing images and videos of meteors, the camera has inadvertently recorded storms, birds, planes, and even fireworks. 'The Museum lights its towers at night, so I was worried that would impede the data,' says King. 'But luckily we've been OK.'
A network of fireball data
The detector is part of the UK Meteor Observation Network (UKMON), which consists of 23 cameras dotted around the country. And there are plans to use the Natural History Museum in Tring to expand the network further.
'This camera is pointing north, and the plan is to install another on the Museum roof in Tring, which will point south,' says King. 'That way when they capture the same event, the data can be combined and scientists can see where the meteor has come from, its rough size and trajectory.'
As well as contributing to Museum science, King is hoping to set up a schools network, with cameras installed at secondary schools around the UK. 'It's a simple and relatively inexpensive setup, so it's ideal for promoting science and technology in schools and gives students exciting, hands-on research experience.
'And, of course, extending the detector network would mean better coverage and more comprehensive data for scientists.'