### If the sun comes too close to the black hole will people really have to start a new world on Mars?

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### Answer from Andrew Telesca, Jr

Adjunct lecturer in physics, Binghamton University

Academic area: Astronomy and physics education

Family: Wife, Lauren, medical technologist, daughter, Heather, photojournalism major, and son, Andrew, mathematics major

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If the Sun did come close to a black hole, it could be a major catastrophe for our Solar System.  Let's talk about the chances of that happening. A black hole is a collapsed star.  The star that becomes a black hole starts out much larger than our Sun, and the black hole itself is several times more massive than our Sun.  Astronomers use the mass of our Sun as the standard, so a black hole is 3 or more times the mass of our Sun.  Mass is how much matter or stuff something has. In terms of size, a typical black hole is much, much smaller than the Earth.  So for our Sun to come close to a black hole and be destroyed, it would have to come very close.  The black hole would have to travel through our Solar System before reaching the Sun and would probably collide with some planets.  The Sun might even start orbiting around the black hole.  Our Solar System would definitely be changed if either of these things happened. What are the chances?  A star that is near our Sun that has a chance of becoming a black hole is Betelgeuse in the constellation Orion, and is about 425 light years away.  A light year is the distance light travels in a year.  A beam of light traveling from the Earth at 186,000 miles per second would take 425 years to get to this star.  Our Sun travels through the Milky Way at a little more than 7 miles per second (that's like going from Binghamton to Owego in 3 seconds).  If our Sun were heading straight for this nearby star, it would take almost 11,000,000 years to reach the star.  But the Sun is not traveling toward this star and the stars that travel with the Sun around the Milky Way keep their distance.  So, the chances of this happening are really small. Some day the Sun will change and expand before it becomes a different kind of a star called a white dwarf.  When this happens, the planets, including the Earth, will also change, each in a different way.  Humans would not be able to live on the Earth like we do now.  Don't worry.  This won't happen for about 5 billion years.  By that time, humans may be living on Mars or even the moons of Jupiter or Saturn. This is only one reason that humans should learn to live on other planets.  Are you interested?  The first astronauts to set foot on Mars are most likely in third or fourth grade now.

Last Updated: 3/1/17