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Page last updated at 16:10 GMT, Friday, 30 July 2010 17:10 UK

Smartphone apps that make sense of the stars

One of the trillions of stars at your fingertips with the latest stargazing apps

By Peter Price
BBC Click

A new host of smartphone applications which map the stars and chart changes in the universe are giving amateur astronomers the chance to be the first to spot new stars and supernovae.

Look up on a really clear night and you can see about 2,000 stars. That sounds a lot, until you realise that there are millions upon millions of stars in the universe.

Two weeks ago scientists spotted a new star and called it "R136a1". They were using the Hubble Space Telescope and the imaginatively-named Very Large Telescope in Chile.

But to explore the wonders of the universe you do not need anything more sophisticated than a decent pair of binoculars or perhaps something like the Meade LX200 telescope.

It costs about $7,000 dollars (£4,500) and is motorised and guided by GPS. After a few minutes of calibration, it can point anywhere in the sky at the touch of a button. The coordinates you need are easy to find on websites like Heavens Above.

It also works in reverse, so if you find something in the sky, enter the coordinates into Stellarium, a free open-source planetarium which can identify the star in your sights.


But setting up these telescopes and websites is a time-consuming and costly business, so app developers have started taking advantage of the inbuilt GPS and digital compass of the smartphone to find nifty ways of navigating the night sky.

Popular stargazing apps
Google Sky Map
Google Sky Map for Android. Just point it skywards to get a map of what you are looking at.
Star Walk for the iPhone - works just as well on older models without a digital compass.
GoSatWatch shows satellites travelling overhead which can be seen even in the daytime.

Tim O'Brien, astrophysics lecturer at the University of Manchester, believes technology is changing the way people view the sky.

"We get any number of phone calls about bright things in the sky. Quite often it is the planet Venus and we advise people to go and download one of these apps and go and have a look.

"In the future, people will just be able to check for themselves. It brings that science right down to Earth for people - it makes them part of it."

At the Royal Observatory in Greenwich, London's light pollution means the main scope is only useful as a research tool on the darkest winter nights.

However, what it is generating though the Flickr photosharing phenomenon is genuinely illuminating. Rookie stargazers are encouraged to join a group on the site and engage in astrotagging - geotagging for the heavens.

Supernovae hunt

Dr Marek Kukula at the Royal Observatory, Greenwich is enthusiastic about the opportunities astrotagging presents.

"It means that anyone's picture of the night sky can actually be tagged with useful information and we can build up an amazing mosaic image of everybody's pictures of the sky, which anybody, amateurs, members of the public or professional scientists can access and use."

An example of astrotagging
An example of astrotagging on Flickr. Photo: johnny9s

Using the astrotags, computers can automatically compare images of the same patch of sky and spot what changes over time. Sometimes, these changes can point to the most exciting thing of all - a newborn star.

Scientists are now relying on these automated comparisons because they do not have the time to manually inspect the huge number of photographs being taken around the world.

But classifying the shape and size of distant galaxies in grainy images is tricky for a computer. Luckily, it is easy for a human and that is where Galaxy Zoo comes in handy.

This iPhone app from the University of Oxford harnesses the power of the human brain to check the thousands of photos generated by the Hubble Space Telescope.

"We have very little time and there is a huge public out there who are really enthusiastic about astronomy and have loads of wasted time sitting on the bus or on the train," said Oxford researcher Joe Zuntz . "It is fantastic to be able to use that time up with doing astronomy, with doing science, no matter where you are."

Galaxy Zoo iPhone app
Galaxy Zoo users will be able to help scientists spot real supernovae

The Oxford team is developing a way to use their apps to hunt supernovae - exploding stars which are visible for such a short time that they need to be identified by human eyes as quickly as possible.

The new app, coming later this year, will send an alert when a photo has been snapped which might contain a supernova.

Mr Zuntz says app users will then help to distinguish whether pictures show real supernovae or not, allowing the team to focus on getting pictures of the new stars in real time.

"We could have someone in Europe tell us whether something is really a supernovae and then by the time night comes to Hawaii we can get one of the massive 8m telescopes there to take a really good look at it and get some fantastic data," he says.

With technology in smartphones improving, stargazing is getting easier all the time - it is no longer the lofty preserve of scientists with big telescopes.

Apps like these could spark a renewed interest in astronomy, allowing us all to explore the extraterrestrial by night and join the hunt to spot supernovae by day.

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