The oort cloud is a giant cloud of particles that orbits the sun beyond the orbit of the planets. It's named after the Dutch astronomer who first identified it.
A flyby is a quick visit by a spacecraft or aircraft. Sometimes a spacecraft will flyby a planet or moon to take pictures or measurements.
Extinctions are events where a species of animal or plant goes extinct. This is a very serious issue because it means that the species is no longer alive and it can't be replaced.
astronomically is used to describe something that is very strange or out of the ordinary. When you say that something is astronomically high, you mean that it is very high in comparison to what is normal.
The word orangish is used to describe colors that are between orange and yellow. It is usually used to describe colors that are a little bit darker than either of those colors.
To shrivel is to make something shrink or to reduce its size. When you shrivel a plant, you are reducing the amount of water that it needs.
Extremophiles are organisms that live in environments that are very difficult or impossible for most other organisms to live in. These environments can include the inside of volcanoes, the bottom of the ocean, and the inside of rocks.
Weirdly is used to describe something that is very unusual or unexpected. When you say that something is weirdly shaped, you mean that it is not the usual shape for that kind of object.