Which of the following describes a nebula?

• A cloud of gas and dust where new stars form
• An oval-shaped cluster of densely packed stars
• An explosion at the end of a giant star’s life
• A star and all the planets that revolve around it

An astronomer finds a new star and uses a Hertzsprung-Russell diagram for classification.
The new star surface temperature is similar to that of the Sun.
The new star also has an absolute brightness 10,000 times greater than that of the Sun.
Which classification most accurately describes the new star?

• White Dwarf
• Main Sequence
• Supergiant
• Giant

A system of stars, gas, dust, and dark matter bound together by gravity is called -

• an asteroid
• a nebula
• a galaxy
• a moon

Elliptical, spiral, and irregular are all classifications of the overall shape of which of the following?

• Stars
• Galaxies
• Nebulae
• Comets

The star, Spica, is highlighted in the Hertzsprung-Russell diagram. According to the H-R diagram, which of the following correctly describes the star, Spica? It is a -

• very small and relatively cool star.
• medium-sized and relatively dim star.
• a yellow, dim main sequence star.
• blue, bright main sequence star.

A spiral galaxy is best described as an extremely large group of stars -

• arranged in arms encircling a dense center.
• all packed into a spherical, dense center.
• arranged in the shape of a flattened ball.
• and gases arranged in no specific shape.