Lecture 1 Flashcards
How many planets in the solar system?
8
How many moons (currently) in the solar system?
290
Definition of a planet
-Orbits the sun
-Has enough mass to be round
-Has enough gravity to clear other objects (of similar size) from its orbit
Definition of a moon or satellite
A celestial body which orbits another body
Why is Pluto no longer considered a planet?
Astronomers began to discover objects of a similar size to Pluto and decided to change it’s category to dwarf planet
How does the Sun produce heat and light?
The sun produces heat and light through nuclear fusion
(The sun is a common star and composed of mainly hydrogen gas)
What type of galaxy is the Milky Way?
Barred spiral
(The galaxy orbits a super massive black hole)
Shapes of galaxies
Spiral, elliptical and irregular
What is in the Local Group of Galaxies?
Andromeda, Milky Way, Triangulum and approximately 50 other dwarf galaxies
What is the Virgo Cluster?
Thousands of galaxies bound together by dark matter
What is an astronomical unit?
It is the average distance between the Earth and the Sun
= 1.5x10^8 km
What is a light-year?
The distance light travels in one year
= 9.46x10^12km
What is a parsec?
It is approximately the distance of three light-years
= 3.086x10^13km
What is the speed of light?
≈ 3x10^8m/s
How old is the universe?
≈ 13.8 billion years
