By the end of this unit, you will be able to know:
A
star is a large ball of gas that generates its own energy by fusing hydrogen
atoms to make helium and held together by its own gravity. Stars come in a variety of sizes and compositions, which determine their
amount of energy and gravity.
The Herztsprung-Russell diagram is a scatter
graph of stars, which shows the relative brightness levels and surface
temperatures among the various types of stars.
Hot clouds of gaseous elements and compounds called nebulae serve as nurseries for stars. As these nebulae spin, they slowly condense, raising their temperature and forming stars.
Galaxies are made of millions of stars, interstellar gas, and dust that stay relatively close together due to gravity. The shape of a galaxy can be classified as elliptical, spiral, lenticular (lens-shaped) or irregular.
Black holes are large objects that form dense gravity wells in space. Their gravitational pull is so strong that even light cannot escape it. They can be observed by the light and energy being given off by the objects they are pulling in. They are thought to be remnants of supernova explosions. They have zero volume but infinite density.
The Sun is a medium-sized star relative to other stars and is located at the center of our solar system. Its position in the Milky Way galaxy is on the edge of a spiral, far away from the galactic center.
Of the 50 stars closest to Earth, the Sun is the 4th largest in mass.
The Sun is approximately 149.6 million kilometers away from Earth, which is the closest distance to Earth than any other star in the galaxy
It takes light an average of about 8.3 minutes to reach Earth’s surface after leaving the Sun.
