Star (def): A spherical mass of plasma held together by gravity. There are several types of stars as shown in the Hertzsprung-Russell diagram, below, that arranges them by spectral type, surface temperature, and luminosity
Some of these, e.g. the giants and supergiants, are so bright they can be seen during the daytime through a telescope (if you know where to look – that’s the tricky part). My article Can You See Planets Or Stars In The Daytime With A Telescope? has more info.
- See Know Your Star Types.