A British-built spacecraft has started a seven-year journey to Mercury, the closest planet to the Sun.
Mercury, the least explored planet in the solar system, is a place of tantalising mysteries.
Here are some of the riddles scientists hope to unravel with the £1.4 billion BebiColombo mission.
– Relative to its small size, Mercury has a huge iron core. Scientists are not sure why.
A leading theory is that early in its history a mighty collision with another object blew away much of Mercury’s mantle, leaving a small planet with a big heart.
– Mercury has a strangely dark surface, much darker than it should be given what is known about its composition. It could be due to graphitic carbon rising up from an early ocean of molten magma.
– X-rays are emitted from Mercury’s surface as a result of bombardment by the solar wind. But they are also seen coming off the side of Mercury turned away from the sun.
It may be that the solar particles are channelled by the planet’s magnetic field, creating a king of “surface aurora”.
– Nasa’s Messenger mission to Mercury discovered odd features called “hollows” – shallow irregular features that seem unique to the planet. They appear bright and young but their origin is unknown.
– Despite having surface temperatures of more than 400C there are suggestions of water ice forming in dark polar craters that never see the sun. BepiColombo should show if this really is the case.
– Mercury is the only rocky planet besides Earth to have a magnetic field, but it’s lopsided. The centre of origin is offset from the centre of the planet by about 20 degrees.
– Scientists think Mercury did not form close to the Sun but migrated inwards from further out. A similar phenomenon has been seen in other solar systems. Studying how this may have occurred will shed new light on the evolution of our solar system.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here