The Sun revolves on its own, and because of its gaseous nature it does not have a regular speed. It spins around its equator every 25 Earth days and 31 days at its poles.
Sound waves cannot travel in the moon, because there is no atmosphere there. So, however louder one shouts, it cannot be heard even at ear-shot distance.
The Earth, like all the planets in the solar system, began to form about 4,600 million years ago. Its diameter measures 12,757 km.
Jupiter is a ball of gases of mostly hydrogen and helium. The great red spot visible on the surface of Jupiter is a huge storm - a giant gas hurricane which is as big as two Earths. It spins faster than any other planet and has the shortest day, just under 10 hours.
The Moon is, on an average, 3, 84, 400 km away from the Earth. Its diameter is 3476 km and the Sun is 400 times farther away from us.
The US space probe Pioneer 10 was launched in 1972. After having gone beyond the orbit of Neptune, it is now directed towards Proximo Centurai, the star at the edge of the solar system and nearest to us. Pioneer 10 will reach this star in about 26000 years, and it is eleven billion km away from the Earth. It is also the first to leave our solar system in 1983.
The distant star Upsilon Andromedae is 44 light years away from the Earth. It has three planets circling it, and one of them is four times bigger than Jupiter.
The Moon spins on its axis in 27.3 days and takes the same amount of time to complete one orbit of the Earth. The days and nights in the moon are roughly 15 Earth days, each in a month.
Sun came into existence about 5 billion years ago. It is expected to exist for another 5 billion years.
A pressurized Space Suit for extra vehicular missions (outside the spacecraft) weighs 47 kg, of which the helmet alone is 4 kg. A special liquid is pumped through a network of tubes, 90 m in length, enabling the astronaut to maintain constant body temperature. The layers of Kevlar and Teflon protect the astronaut from cosmic radiation and grains of intergalactic dust.
