In the direction of Serpens Cauda, there is a small unassuming star with the designation BD-01Â°3474, also known as Gliese 710. It is a small reddish star, only about half the mass of the Sun, and shining with only a bit more than 4% of the Sun’s light. It is what astronomers call a K7 dwarf. At a distance of about 50 lightyears, it appears only as magnitude 9.66 in our sky (The naked eye can only see a bit dimmer than magnitude 6 in good sky conditions). There really isn’t anything special or remarkable about this star, except for one thing: it is heading nearly right towards us at about 24 km/s (about 54,000 mph).
Gliese 710 isn’t on an exact collision course, but it will pass very close. In about 1.4 million years, it will be only about 1 lightyear from the Sun. Compare that with the current nearest star which is a shade over 4.2 lightyears away. At one lightlyear distant, this tiny star will shine at about magnitude 1.2 in our sky. That’s slightly brighter than the belt stars in Orion, and just dimmer than Aldebaran. It’s about the same brightness as Deneb or Fomalhaut.
But, becoming one of the brightest stars in the sky isn’t really the biggest news about this star. Our Solar System is believed to be surrounded by a swarm of small icy bodies called the Oort Cloud. When these bodies are disturbed in their orbits, they they can hurl down into the Solar System. There, they become comets. The outer edge of the Oort cloud is hypothesised to be somewhere around half a lightyear out. So, as Gliese 710 passes by, it will be nearly as close to these Oort cloud objects as is our own Sun. Gliese 710 has less mass, but it still has a LOT of mass (half the Sun’s mass) with which to disturb orbits. It will disturb a lot of orbits. In fact, this could produce a swarm of comets heading towards the inner Solar System. It might even be pretty for any inhabitants of the Solar System then, as you might expect a spectacular comet every couple years. There might even be almost always a naked eye comet somewhere in the sky. Very pretty indeed. Until one of them runs into us.
Granted, we are a small target, so such a collision is unlikely, but the more objects that are flying around the greater the chances. But, this is still a long way into the future.
(Image: Palomar Digitized Sky Survey)