Re: Why is Venus the hottest planet,and Mercurey is more near the sun?

Great question Sara.

Venus' average surface temperature(~850 degrees F) is higher than Mercury's average surface temperature because, although Mercury is closer to the sun, it has virtually no atmosphere to hold heat in. Venus has a thick blanket of carbon dioxide, water vapor, sulphur dioxide and sulphuric acid particles which trap all of the heat the planet collects. This is an extreme case of what atmospheric scientists call the "Greenhouse Effect."

Since Mercury has virtually no atmosphere, it loses most of the heat it collects during the day at night time. Daytime temperatures on Mercury can be up to 800 degrees F. At night the temperature plunges to -300 degrees F. So although one half of the planet is scorching hot, whichever side happens to be facing away from the sun is freezing cold. I hope this answers your question. For more info on the first astronomy, check out this cool website: www.itss.raytheon.com/cafe/qadir/qanda.html

Happy Learning! -Paul Barrett paul_barrett@pacsci.org