Stars, Constellations and Galaxies

Question 1

What is a galaxy?

Answer 1

A galaxy is a collection of gas, dust, billions of stars, planets and other celestial objects spread across the universe

Question 2

What are the four different types of galaxies?

Answer 2

Spiral galaxy
Elliptical galaxy
Irregular galaxy
Lenticular galaxy

Question 3

What are characteristics of an elliptical galaxy?

Answer 3

• oval
• oldest galaxies
• contain little gas, dust or young stars
• this type accounts for half of all the galaxies

Question 4

What are characteristics of an irregular galaxy?

Answer 4

• have no definite shape
• contain the most gas and dust
• make up at least 10% of all galaxies

Question 5

What are characteristics for a spiral galaxy?

Answer 5

• flattened discs with a central bulge made of all stars
• look like spinning pinwheels
• 2-4 spiral arms made of young stars
• a subclass of these are barred galaxies, which is our galaxy, the Milky Way Galaxy

Question 6

What are characteristics of a lenticular galaxy?

Answer 6

• flat disc

- made of old stars

Question 7

How can you determine the composition of a star?

Answer 7

By looking at the electric magnetic spectrum; every element emits it’s own colour pattern (spectral lines) so looking at spectral lines can determine the composition.

Question 8

How is a star’s lifecycle similar to ours?

Answer 8

Stars are born, they evolve, then they age and finally, they die similarly like a human’s life.

Question 9

What is the beginning of the formation of a star?

Answer 9

1. All stars start as a nebula.
2. Gravity pulls the nebula to the centre and squeezes the matter together.
3. The pressure and temperature increases enough until a nuclear fusion begins.
4. The result is a protostar.

Question 10

What is the final outcome of a star depends on?

Answer 10

It depends on its mass; the more massive the star, the faster its rate of fusion which results in a shorter life cycle.

Question 11

What is the sequence of events for small stars?

Answer 11

Red giant, white dwarf, white dwarf cools and fades

Question 12

What is the sequence of events for a large star?

Answer 12

Red supergiant, supernova, neutron star

Question 13

What is the sequence of events for a very large star?

Answer 13

Red supergiant, supernova, black hole

Question 14

What is a H-R diagram?

Answer 14

A graph that shows where stars are ranked according to their temperatures and brightness (luminosity)

Question 15

How many official constellations are there?

Answer 15

88

Question 16

Who is responsible for naming constellations?

Answer 16

The IAU (International Astronomical Union)

Question 17

What do constellations represent and originate from?

Answer 17

Greek and Latin origins

Mythological figures

Question 18

What asterisms?

Answer 18

Star patterns within a constellation

Eg: Ursa Minor contains the Little Dipper and Ursa Major contains the Big Dipper