{"id":45424,"date":"2023-05-29T07:40:06","date_gmt":"2023-05-29T07:40:06","guid":{"rendered":"https:\/\/www.skyatnightmagazine.com\/?p=119022"},"modified":"2023-05-29T08:32:32","modified_gmt":"2023-05-29T08:32:32","slug":"a-beginners-quick-guide-to-cosmology","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/a-beginners-quick-guide-to-cosmology\/","title":{"rendered":"A beginner\u2019s (quick) guide to cosmology"},"content":{"rendered":"

When did cosmology begin, and what do cosmologists study? <\/p>

By Marcus Chown\n \t\t<\/p>

Published: Monday, 29 May 2023 at 12:00 am<\/p>

\n\n

Cosmology is the field dealing with the Universe on large scales: its origin, evolution and properties.<\/p>\n

Astronomy, on the other hand,\u00a0 <\/span>is the study of celestial bodies, while astrophysics is all about the physical and chemical properties of these bodies, including their luminosities and their chemical compositions.<\/p>\n

Since the behaviour of the Universe on large scales is orchestrated by gravity<\/a>, there could be no serious science of cosmology until someone came up with a description of gravity that was totally accurate.<\/p>\n

That person was Albert Einstein, who in 1915 published his general theory of relativity and, the following year, applied it to the Universe as a whole.<\/p>\n

Einstein, however, didn\u2019t know that our Milky Way<\/a> was a galaxy<\/a>, and that galaxies were the basic building blocks of the Universe.<\/p>\n

This discovery was made in the 1920s by the American Edwin Hubble<\/a>, who also found the galaxies were flying apart like so many pieces of cosmic shrapnel.<\/p>\n