In what sense are the quasars Quasi Stellar?

Quasars, or quasi stellar objects, are named that way because they are point-like objects just like stars. However, they are nothing like stars. From analysis they are determined to be very distant, some are the most distant objects that we can see. But they are also very bright.

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Keeping this in consideration, why do galactic disks appear blue?

Harlow Shapley found the Milky Way was: much larger than previously thought. Galactic disks appear blue because: They believed that the Milky Way was the entire universe. What's the difference between dark matter and dark energy? Dark matter and dark energy are the yin and yang of the cosmos. Dark matter produces an attractive force (gravity), while dark energy produces a repulsive force (antigravity). Together, they make up 96 percent of the universe-and we can't see either.

What is the difference between baryonic matter and dark matter?

Baryonic Matter vs Dark Matter First and foremost, baryonic matter are composed of baryons ? mostly protons and neutrons. However, the composition of dark matter is yet to be discovered. What is antimatter and dark matter? Antimatter is also produced by lightning and cosmic rays. It is well understood by physicists, and is predicted by standard particle physics theories. Dark matter is matter that does not interact electromagnetically, and therefore cannot be seen using light.

What are RR Lyrae and Cepheid variable stars and why are they important to understanding the universe?

Key concepts and summary Light curves of these stars show that their luminosities vary with a regularly repeating period. RR Lyrae stars can be used as standard bulbs, and cepheid variables obey a period-luminosity relation, so measuring their periods can tell us their luminosities. Are variable stars necessarily on the main sequence? Above the main sequence, the vast majority of stars in the instability strip are variable. Where the instability strip intersects the main sequence, the vast majority of stars are stable, but there are some variables, including the roAp stars.