Question

Globular clusters of stars rotate about most galaxies just like planets rotate about the Sun. The mass of the galaxy needed to keep them in orbit is much greater than the known mass of the galaxy. In fact, only few percent of the necessary mass can be seen. The missing mass is

• A. found in black hole.
• B. is called black matter.
• C. is called dark matter.
• D. is called dark mass.

Answer 1

Answer: (C)

is called dark matter.

Dark matter is a kind of matter that cannot be seen with telescopes but would account for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe.

So dark matter which constitute most of the mass of universe is the missing mass needed to keep globular clusters of stars in orbit around galaxies.