Earth's inhabitants should survive close encounter, academic says

A USQ academic believes the probable close encounter of a nearby star with our solar system will pose little or no hazard to Earth's future inhabitants.

Biological and Physical Sciences Senior Lecturer, Dr Brad Carter, was commenting on a new study released by the Pulkovo Astronomical Observatory in St Petersburg last week, which suggested a star known as Gliese 710 could disrupt planetary orbits and send a shower of comets and asteroids towards the inner planets when it passes in 1.5 million years' time.

'Gliese 710 is a cool red dwarf star that is one of many billions in the Milky Way galaxy,' Dr Carter said.

'This star's likely close approach to our solar system 1.5 million years from now is the sort of event that can happen many times during the 10 billion-year lifetime of our Sun.

'This is because as our galaxy rotates, the Sun shares its region of our Milky Way galaxy with millions of other stars moving at relative speeds of kilometres per second in various directions.'

Dr Carter said that while the approach of Gliese 710 should disturb our solar system's Oort cloud of comets beyond Pluto, and increase the chance of a comet changing its orbit and hitting the Earth, the reality is that the increased hazard to Earth's future inhabitants is small.

'This is something like a five percent greater chance of an impact than today.'

While this event was unlikely to disrupt human life, Dr Carter said astronomers were constantly scanning the skies for possible threats to Earth.

'Gliese 710 reminds us that over very long timescales humanity needs to be aware that comets or asteroids can and will hit the Earth and cause great damage, with the most famous example being the extinction of the dinosaurs 65 million years ago.'

Dr Vadim Bobylev, of the Pulkovo Astronomical Observatory in St Petersburg, is the author of the recent study, which has been submitted to the journal Astronomy Letters.

Dr Bobylev estimated that the likelihood of an impact between Gliese 710 and the outer edge of our solar system to be as high as 86 percent, basing his calculations on data collected by the European Space Agency's Hipparcos spacecraft.

Measurements made by the spacecraft were used to create the Hipparcos catalogue, which contains detailed position and velocity measurements of 100,000 stars in our neighbourhood.

According to the catalogue, there are 156 stars that either have or will make a close approach, which appear to occur once every two million years.

In 2007, the Hipparcos data was revised and combined with new measurements of star velocities.

Dr Bobylev combined this data with several new databases, finding an additional nine stars that either have had, or will have, a close encounter with the Sun.