Stars are grouped according to their spectral characteristics by single letters of the alphabet, optionally with numeric subdivisions.

The seven main types of stars. How they’re classified and their roles in stellar evolution, lifecycle stages, and how they appear in the night sky.

Dec 18, 2025 · Scientists call a star that is fusing hydrogen to helium in its core a main sequence star. Main sequence stars make up around 90% of the universe’s stellar population. They range in …

Dec 4, 2025 · From hot stars to cool, the order of stellar types is: O, B, A, F, G, K, M. (A traditional mnemonic for this sequence is “Oh Be A Fine Girl [or Guy], Kiss Me.”) Additional letters have been …

Using the letters O, B, A, F, G, K, and M, the 7 main types of stars are easily classified from hottest (O) to coolest (M). The temperature of each spectral class is then further subdivided from hot to cool by …

May 3, 2025 · Along the way, we’ll explore the types of stars that fill our galaxy, their brilliant life cycles, and some astonishing facts that make stars among the most fascinating objects in all of nature.

Aug 29, 2025 · When you look up at the night sky, you’re seeing just a small sample of the incredible variety of the types of stars in the universe. These cosmic powerhouses come in wildly different …

Stars are grouped into 7 main categories (also called classes), created by astronomer Annie Jump Cannon. The classes are called O, B, A, F, G, K and M. Stars in the 'O' class are the most massive …

With the development of spectroscopy, a new way of classifying stars came into being: stars were classified by the features of their spectra. This is the meaning of the obscure jargon of astronomers …

Jul 26, 2025 · Let’s look at those non-alphabetical star types! Note that for this section we’re looking specifically at main sequence stars, ones in the middle of their lives. We’ll start with the O stars.