Astronomy/Star Systems

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Expert: Jesse Martinez - 1/24/2010


Question
Why don't star systems collide more often?

Answer
Hello Mary. You have an interesting question. I think if I explain the scale of our galaxy and stellar distances you would immediately see why this doesn't occur often.

Stars are far apart from each other. There is so much space between them that the odds of a collision are very remote. I will use our sun and our nearest stellar neighbors in the Centauri system as an example. One of the three stars, Alpha Centauri is about our sun's size, a little under a million miles in diameter. Our sun is 865,000 miles across. The two stars are 4.3 light years away from each other. A light year is 5,878,630,000,000 miles. 4.3 light years would be 25,278,109,000,000 miles. If we changed the scale of the two stars so they are the size of peas, about 0.25 inches across, they would be two peas separated by a distance of 115.3 miles! 25,278,109,000,000 miles / 865,000 miles = 29,223,247 sun diameters to Alpha Centauri. If the sun is 1/4 inch across it is 29,223,247 X 0.25 inches away, 7,305,812 inches. There are 63,360 inches in a mile. 7,305,812 inches / 63,360 inches per mile= 115.3 miles. You can see how a collision would be unlikely, especially since the stars in our galaxy are generally not moving towards each other.

Galaxies are more likely to collide. Our galaxy and the Andromeda galaxy are comparable, in a reduced scale like above, as two dinner plates 30 feet apart, a much more imaginable scale. It is also one where collisions can actually occur. This site has information on galactic collisions. http://en.wikipedia.org/wiki/Interacting_galaxy  

You can also Google images for colliding galaxies.

Thanks for the question, I enjoyed answering it.

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Jesse Martinez

Expertise

General and specific questions about the solar system and stellar and galactic astronomy, are what I can easily answer off the top of my head. For example, what is the largest planet in the solar system? How far away is the moon? Have there been any confirmed planets in orbit around stars other than the sun? How many stars are there? The tougher ones like explaining the big bang theory and black holes I will leave to the PhD’s. Even though I could muster an answer, I would have to research it more than I would like. I would also like to answer questions that involve Astronomy with other sciences, chemistry, biology, physics, geology and mathematics as long as they are not PhD level.

Experience

I have been into astronomy since I was 8 years old. I have kept detailed journals of my observations through small telescopes. Over the years I have participated in amateur observation projects for organizations like ALPO. My personal research has involved "discovering" the moons of Jupiter with a 4½-inch Newtonian reflector without any outside information like charts and tables. In a summer long project, I determined the existence of and plotted the orbits of the four major moons of Jupiter. From these observations, my data on orbital elements was surprisingly accurate (orbital radius and orbital period).

Education/Credentials
80 hours of college credits while studying physics and geophysics. Completed correspondence photography course while in high school. Took two semesters of electronics training at a community college. Studied computers and graduated from a technical school at the turn of the millennium, gaining A+ and Microsoft Certified Professional credentials. Hablo Español. Si quieres preguntar en Español, estoy a su servicio.

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