The planet called" Earth Twin" is called Venus. Venus is the most alike planet to earth density and size. Another name for Venus is the "Evening star" because not only it's the closest to look like each density and size it also the closest planet to earth. So at night you can look you and see Venus. Venus even had some spacecraft send to the planet but Noe of the survived the landing on the planet over three decades.

This planet surface and atmosphere both have ext ream conditions. The atmosphere of Venus is 97 percent carbon oxide and the clouds rain corrosive surface acid. And the surface is over 800 degrees Fahrenheit and the pressure is 90 time than earth. Even thought Mercury is closer to the sun Venus has the hottest surface. And that's because of the weather patters and the volcanos. Or it because the powerful earthquakes or the lighting strike.

The NASA want to still try to send thing to this planet it lair thing they can't touch. They know the probably they have to solve before they really send anything up there. There was people in the 1800s trying to figure out Venus history and people even going over that to see if they miss anything. A lot of researchers was trying to past the challenge but didn't know how because the heat of the planet was messing up the rocket they are sending and there trying to finger out that problem now.