The rocky planets of our solar system: Mercury, Venus, Earth and Mars.

Mercury is the smallest planet in our solar system. It is also the planet that is located closest to the Sun. As a result of its closeness to the Sun, its orbit is the shortest in the solar system: a year on Mercury only takes approximately 88 Earth days. The days on Mercury are longer than those on Earth. This is a result of the planet's slow spin rate. A day on Mercury is approximately 58 Earth days long. Mercury is the only rocky planet without a gas atmosphere, which subjects the planet to large temperature changes. The difference in temperature between day and night can be as stark as 600 degrees, with days as hot as 420 degrees and nights as cold as -170 degrees. Mercury has no moon.

The size and composition of Venus resemble those of planet Earth. It is the brightest "star-like" object on the night sky, and it can sometimes be seen even during the day. The temperature on the planet's surface can reach over 500 degrees Celsius. This is due to the high carbon dioxide concentration of the planet's atmosphere, which results in a powerful greenhouse effect. Venus does not have a moon.

Earth is a blue planet. Most of its surface is covered by liquid water. It has an atmosphere and a magnetic field that protect it from solar radiation and meteoroids. It is the only planet where life has been found. Its orbit around the Sun lasts for 365 days and 6 hours. It rotates around its axis over the course of 23 hours, 56 minutes, and 4 seconds. The average temperature on the planet's surface is 14 degrees. It has one moon. 

The red color of Mars is caused by iron dust found on its surface and in its atmosphere. It accomodates water in both gaseous and solid form. Its atmosphere is thin and consists mainly of carbon dioxide. The average temperature on the planet's surface is -55 degrees Celsius. Mars has two moons, Phobos and Deimos.​