This stunning photo shows every single planet in the solar system at the same time during a rare alignment that won’t happen again until 2040. Taken from a field in Somerset, the groundbreaking ...

So, even though Mercury is closer to the Sun, Venus is the hottest planet in the solar system. Mars has a hard, rocky surface with lots of iron in the soil which rusts, making the surface and ...

With a radius of 2,106 miles, Mars is the seventh largest planet in our solar system and about half the diameter of Earth. Its surface gravity is 37.5 percent of Earth’s. Mars rotates on its ...

The discovery that helium and iron can mix at the temperatures and pressures found at the center of Earth could settle a long-standing debate over how our planet ... of our solar system's comets ...