What would the weather be like on a planet in a binary star system?

Question

I'm off to Alpha Centauri soon (http://uk.answers.yahoo.com/question/index;_ylt=Ao5Q7zESdw_RBMk2RXQVq6sgBgx.?qid=20060724154615AAYSZni ) and I need to know what to pack. Here's the problem:

Our planet orbits our single sun in a modest little ellipse. The resulting variations in the solar radiation we get are not huge, so our climate is able to be reasonably consistent over the seasons. Yet still we have heat waves, hurricanes, big freezes, etc. And it doesn't take much (just one measily little asteroid impact) to wreck the weather so much that most things die.

What about planets in binary star systems? Surely the variations in radiation at different points in a planet's orbit would be enormous, giving the planet such bonkers weather that life would be impossible? or at least, very very awkward?

Answer 1

It really depends on the configuration of the star system.

THIS WILL WORK:
With a close binary, a G type star, equal in mass to our sun with a small red M type star with 0.2 solar masses with a separation of 0.1 AU, would not be a problem. This would be a 10.54 day period. An earthlike planet at 1.0 AU would be fine with an orbit period of 333.4 days. Bear in mind that the small cool star will never get closer to the planet than 0.9 AU. Most of the time you would get 2 sunsets and 2 sunrises which would look spectacular.

It would also work with the same stars with a wide separation. The planet could orbit the G type star at a distance of 1.0 AU with the M type companion at a distance of 5 AU. On many occasions the red companion would be visible at night, making sleep a bit more difficult for some.


THIS WOULD NOT SUPPORT LIFE:
A possible chaotic configuration would be a figure 8 orbit between 2 stars of nearly equal mass. Temperatures would fluctuate wildly from freezing to boiling hot.

Answer 2

Now for something a bit more realistic. First up, in order to have a habitable planet in a stable orbit in a binary system, there is going to have to be a minimum separation of the two stars. Given Alpha Centauri as an example, this is possible, as the two primary stars are separated by about the distance from the sun to Uranus in our own solar system. Planets could have a stable orbit around either star to a distance of maybe 200 million miles, which is within the "habitable zone."

Notwithstanding the arguments that it may be unlikely for large planets to form in a such a binary system, let's just assume that a nice cozy planet did come about for our enjoyment, at a distance similar to where Earth is in our system. The real answer to the situation is that the second, farther star, isn't going to have a great influence on the weather...it's simply too far away. The most notable effect would be the light, which would still be very bright...certainly too bright to look at directly. Truely dark nights would only occur about one-quarter of the time, when the two stars are in relative alignment. And for another quarter of the time, there would always be at least one of them in sky, meaning no night at all.

All that said, however, any effect the farther star would have on weather patterns would pale in comparison to the much closer primary star. Sure, there might be some effect, but for the most part the second star would simply moderate the extremes imparted by the dominant star. Nights would not get quite as cold when the second star was up...but they certainly would get colder.

Lastly, with Alpha Centauri as the example, it would be impossible to have a habitable planet in orbit about both stars...it would simply be too far out and be too cold. However, if it were a moon of a warm gas giant, then all bets are out...but that's another scenario entirely.

Answer 3

There are 3 possibilties.

1) The 2 stars are close together and the planet orbits around both of them. In this setup, the planet would have a normal day/night cycle, except the sunset and sunrise would be double. One sun would pop up at sunrise, shortly followed by another. Now, assuming the suns are quite cool, so the combined heat from them as the same as our sun, the weather of the planet ought to be the similar to Earth. There may some "solar-seasonal" variations where one of the suns passes behind the other as seen from the planet. This would cause a temporary cooling, so the planet may have more than 4 seasons because of this. Planet Tantooine in Star Wars is like this, but is hotter than Earth because the 2 suns heat combined is more than our single sun.

2) The 2 stars are far apart, and the planet orbits just one of them. In this case, the day/night cyle of the planet is just like Earth. A single sunrise and sunset of the primary star. The secondary star would be seen in the night sky for most of the year. This would mean night time on the planet will not be truly dark, except for a few weeks each year when the second star appears to slip behind the primary as seen from the planet.

3) The planet sits in the Lagrange point between the 2 stars. A Lagrange point is a point in space where the gravity of the stars cancel each other out (in fact there are 5 for any 2-body system). assuming the planet sits in the Lagrange point that exists with a star on either side, the planet will have no night, ever. Not only that, it would probaly be tidally locked from rotation (the stars gravity stops the planet from turning). Each side of the planet will see a sun which would never move. Kinda boring to live in I think.

Answer 4

The odds of winning the Lotto are one in 14 million, but someone wins most weeks. Why? Because somewhere around 14 million people play with several combinations of numbers, so the chance of you winning remains low, but the odds of SOMEONE winning are almost 1 in 1. With the trillions of stars and billions of galaxies in the Universe, what are the odds that at least one solar system won't contain such conditions? Practically none. And we'd have evolved on whichever system allowed the conditions for us.

Answer 5

yes like in Pitch Black, the movie, the planet is in a binary star system. Let's just say skin cancer will be rife

Answer 6

the weather intensity/effect is greatly affected by the distance from the planet to the suns.

Answer 7

On a binary planet, I imagine it would be:

0100011100001111100000000111111111111000000111111......and so on...................

Answer 8

You won't have to turn over to get a tan on both sides.

Answer 9

Fuckin Freezin