Galaxies and cosmic distances – basic principles
How it works
Galaxies are huge collections of stars, gas, dust, and dark matter held together by gravity. Our home galaxy is the Milky Way. There are various types of galaxies, for example spiral galaxies, elliptical galaxies, and irregular galaxies. Distances in the universe are so large that they are often given in light-years — a measure of how far light travels in a year. The distance to distant galaxies can be estimated using various methods, such as observing standard candles like Cepheids or certain supernovae. On large cosmic scales, many distant galaxies show redshift; this is an important indication of the expansion of the universe.
Galaxies are classified according to their shape. Large cosmic distances are often given in light-years; for distant galaxies, standard candles and redshift are used, among other things, as clues to their distance.
An example
Which statement correctly describes a spiral galaxy?
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50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Astronomy. The topic assignment may vary by federal state.