How big a change in the Earth's orbit would be required to destroy all life?
In this question you talk about the fact that 500-1000 miles variation of the distance between Earth and Sun would not cause catastrophic temperature variations. What distances would? How much variation would be needed to extinguish life as we know it?
That's a pretty tough question to answer, because the effect of orbital variations on climate is not very well understood. We know that small changes in the eccentricity of Earth's orbit (that's a measure of how much the Earth's orbit is an oval, rather than a circle) can cause ice ages, but how big a change would it take to cause a permanent ice age, or to raise the Earth's temperature enough to cause a runaway greenhouse effect, like we see on Venus?
The habitable zone is the region around a star in which water will be liquid at the surface of a planet. The habitable zone around the Sun (depending on how you calculate it) is about 0.95 AU to 1.37 AU. An AU is the Earth's average distance from the Sun, 93 million miles, so the Earth's orbit could decrease by 4,500,000 miles or increase by 34,000,000 miles and still be in the habitable zone.
A large change in the Earth's orbit would have big consequences for our climate, and would lead to the extinction of many species. However, to destroy all life on Earth the orbit would have to change by at least hundreds of thousands of miles.
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
- How critical is the Earth-Sun distance in maintaining our average temperatures on Earth?
- How do you measure the distance between Earth and the Sun?
- How can I find the distance to the Sun on any given day?
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 31874 times since November 15, 2002.
Last modified: September 5, 2006 8:00:31 AM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)