1.In 3.75 billion years, the Milky Way and Andromeda galaxies will collide.
The Andromeda Galaxy is approaching the Milky Way- where our solar system is at a rate of around 110 kilometers per second (68 mi/s) and, the two will collide to form a giant elliptical galaxy.
2.Andromeda is probably the most massive galaxy in the Local Group.
There are around 1 trillion stars in the Andromeda galaxy, compared with the Milky Way, which has 200-400 billion.
3.If two pieces of the same type of metal touch in space, they will permanently bond.
This incredible fact is also known as cold welding, and it happens because the atoms of two pieces of metal have no way of knowing they are separate. It doesn’t happen on Earth because of the air and water found between the pieces.
4.The Moon was once a piece of Earth.
The theory is that when Earth was a relatively young planet, was struck by a giant object, and this collision broke a piece of the Earth away to create the moon. This piece then began to orbit the Earth as a result of its gravitational pull.
5.Space is completely silent.
Sound waves need a medium to travel through. Since there is no atmosphere in the vacuum of space, the realm between stars will always be eerily silent. Astronauts use radio waves to communicate.
6.The Apollo astronauts’ footprints on the moon will probably stay there for at least 100 million years.
Since the moon doesn’t have an atmosphere, there’s no wind or water to erode or wash away the Apollo astronauts’ mark on the moon. That means their footprints, overprints, spaceship prints, and discarded materials will stay preserved on the moon for a very long time. Erosion is still happening on the moon, just very slowly.
7.Some planets have no surface to land on.
There are four gas giants in our solar system — Jupiter, Saturn, Uranus, Neptune — where it wouldn’t be possible to land on. Although different in composition, a gas giant is usually made out of hydrogen and helium and has a small rocky center.