Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

Hot Times on Io


Sign up for our email newsletter for the latest science news

This high-resolution image of Jupiter’s moon Io was snapped last November 6 by the Galileo spacecraft, and it has given astronomers their best look at the most volcanically active object in the solar system since the Voyager flyby in 1979. The two small spots in the image’s lower left are volcanic calderas, collapsed depressions usually associated with hot spots. The calderas are dark because they are probably still filled with hot lava that has boiled away lighter-colored sulfur dioxide frost. In the upper left is an outpouring of lava some 250 miles long. Such massive lava flows are also known to have occurred in Earth’s past, but they have never been observed. Some researchers have proposed that these lava floods caused global extinctions on Earth and that they affect climate change, says planetary geologist Alfred McEwen of the University of Arizona, head of the Io observation team. So rather than waiting around for another 100,000 years for one to occur on Earth, we can observe Io, where they are happening today.

    3 Free Articles Left

    Want it all? Get unlimited access when you subscribe.


    Already a subscriber? Register or Log In

    Want unlimited access?

    Subscribe today and save 70%


    Already a subscriber? Register or Log In