Wondering about wild grapes

Tuesday, January 11, 2011

Wondering about the Habitable Zone

It is way beyond luck that we live where we do. This planet of ours is in the right place to sustain life as we know it. And life it has in every shape and size and located in every nook and cranny on the land and in the sea. The location of planet Earth is just inside the habitable zone of our nearest star, the Sun.

What is a “habitable zone”? Scientists describe it as a zone that allows liquid water to exist on a planet. Or words to that affect. I would just say that it is the area around a star that life can survive.

Now that doesn’t mean that we will always be safe. Notice that I said “just” inside the habitable zone? We are very close to the hottest edge of the “zone” and we better hope that nothing makes us move to a tighter orbit or that the sun doesn’t speed up its slow expansion. Yes, the sun is now slowly expanding and getting brighter. The key word here is “slowly”.

Here is a picture that was taken from “Astronomy” magazine showing the sun, the habitable zone, and the orbits of the four planets that are closest to the sun:

As you can see, Earth is the only planet that stays within the zone for its complete orbit. But notice that the orbit is close to the hot side and at part of its orbit, it gets very close to leaving the zone. That would put us in a very precarious position, especially since the sun is growing larger.

All sorts of things can happen to change orbits. Although space is almost empty, it does contain matter and other things like the solar wind, cosmic radiation, and other forces that act ever so slightly on the earth. This orbital friction can slow a planet and decrease its orbit which will, in turn, allow it to keep its momentum. The moon is moving away from us, and we are constantly being bombarded with stuff from space, hopefully all small stuff and hopefully not enough to change our velocity or mass.

Of course, we are also lucky that we are on the hot side of the zone. Just think how cold this winter would have been if we were way out there on the cold side?!?!


  1. Does give you something to ponder on, doesn't it? I don't want to be farther away from the sun than we are right now, I think!

    Can't handle too much more of the cold than I get right now!

  2. Yes Jim, I am pretty much satisfied with our place in the universe. . .

  3. Dizzy INFINITY the unknown is hard to understand an harder to comprehend.All our scholars knowledge on the subject you probably could put on the head of a pen.(This I believe) an I don't know nouthing.

  4. Wonder what ole Al "I invented the Internet" Gore has to say about all this Global warming trend now ?
    Or does he do any Scientific research?

  5. Ted, I just read a really funny article about infinity. But I know better, infinity is where everything goes that I can't find. . .

    Ben, What would we do without people like Gore? It would not be as humours a world as it is today. Got to have someone to laugh about and the politicians are filling the bill.

  6. Very interesting post! I'm not sure what would be worse...instantly burning or freezing (but I'm not ready to find out).

  7. Ben Gore did have a lot to do with getting computers in to the schools.At that time he forsaw the importance of the internet.He did not invent the internet,but he had a lot to do with the funding for computers to the schools .

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  9. Ezrablu, I know you wouldn't want to be burning hot, but I thought that you were use to freezing.

    Ted, thanks for the info.

    Ben, must have been really bad if you removed your own post. (grin)

  10. We are spiraling into the sun ya know. We have 2 billion years before we hit that hot zone