Astronomy for Beginners
Here’s where you’ll find observing guides, how-to articles and great astronomy hints and tips. Don’t forget to also check out our comprehensive astronomy dictionary.
These are thin clouds of ice and dust particles that are so high in the Earth’s atmosphere that they are bright during twilight, in the early summer months (dusk, and just before dawn).
This is the name given to the projection of the night sky on to an imaginary sphere around the Earth. The astronomical co-ordinates of right ascension and declination are also mapped on to this sphere.
The point where the pressure of the local interstellar medium overwhelms that of the solar wind, stopping it from expanding any further out into space.