Neighboring Magellanic Clouds Important to Earth Astronomers

The Large and Small Magellanic clouds are relatively close galactic neighbors of the Milky Way, the galaxy in which Earth’s system is found.  Anyone wishing to see them from the surface of the planet will need to be located south of the equator; they are only visible from the southern hemisphere.

Different structures

On visual inspection, both of these clouds appear merely as wisps of vapor in the night sky, and their lack of the usual structures associated with islands of billions of stars leads scientists to believe they are changing into star clusters.  More importantly, this transition is happening close by, where it can be studied for clues to the dynamics of such bodies and the star systems contained within them.

“They might as well have been tailor-made laboratories to test our ideas about the evolution of stars – huge collections of stars of all ages and luminosity, all at just about the same distance from us so that we can compare them to each other free of the uncertainties due to distance which enter so easily when we study various populations in our own galaxy.”

Cepheid variable stars

These are very bright stars whose rate of variability in brightness was studied in the early 20th century.  The scientist examining these stars (Henrietta Leavitt, 1912) found that their pulsation period was related to their brightness, a fact that led Edwin Hubble to the discovery of other galaxies beyond the Milky Way, beginning with Andromeda, about two million light years distant.  “The Cepheids in the Magellanic Clouds are still the zero point for these distance measurements.”

Intergalactic destruction and star formation

There is a stream of gas encircling one-half of the Milky Way, and scientists have determined it was stripped from the Small Magellanic Cloud.  It is known as the Magellanic Stream, and there continues to be research seeking to pin down which larger body is responsible for the Stream, the Milky Way or the Large Magellanic Cloud. 

“’Studying these galaxies offers us the best opportunity to study star formation outside of the Milky Way,’ said Margaret Meixner, an astronomer at the Space Telescope Science Institute, Baltimore, MD.”  The Clouds are located between 160,000 and 200,000 light years from the Milky Way, putting them much closer to optical instruments like the Hubble Space Telescope and other devices used to study space objects using radio waves.

The Magellanic Clouds have not given up all of their secrets.  Scientists will continue to use these nearby stellar objects for studies in different disciplines, advancing knowledge and adding to the inspiration to learn more about all aspects of the universe.