I'm not so sure, given the article as written. Comparing Earth and Jupiter: 1. made up of about three-quarters liquid water False for both. Possibly true f

I'm not so sure, given the article as written. Comparing Earth and Jupiter: 1. made up of about three-quarters liquid water False for both. Possibly true for Earth if you're talking about surface area, but that's a pretty generous interpretation of the article as written. 2. with a solid core of iron and nickel Likely true for both. ("At the center of [Jupiter's] rocky core is probably a metallic ball of iron and nickel, just like Earth's core." http://www.spacedaily.com/reports/Jupiter_Has_Large_Rocky_Core_Surrounded_By_Layer_Of_Ice_999.html http://www.spacedaily.com/reports/Jupiter_Has_Large_Rocky_Co...) 3. an atmosphere of hydrogen and helium True for Jupiter, not for Earth. That's 2 of 3 for Jupiter, 1 of 3 for Earth (or 2 of 3 for Earth if you're being generous). Mars sounds a lot more like Earth than GJ 1214b does, based on the article. GJ 1214b might be more like Earth than any other known exoplanet, but given the murky reporting it's hard to tell.