Lecture 1 Flashcards
(10 cards)
What is the overall structure of the universe starting from Earth?
Earth orbits the Sun within the solar system, which is part of the Milky Way galaxy. The Milky Way is one of trillions of galaxies in the universe, which together form galaxy clusters and superclusters.
What is a light-year?
A light-year is the distance that light travels in one year, approximately 9.4 trillion kilometers.
How far is the Moon from Earth in light-time?
The Moon is 1.5 light seconds away from Earth, which is about 450,000 kilometers.
How far is the Sun from Earth in light-time?
The Sun is 8.3 light minutes away from Earth, which is about 150,000,000 kilometers.
How far is Pluto from Earth in light-time?
Pluto is about 5.5 light hours away from Earth.
How far is the nearest star from Earth?
The nearest star, Proxima Centauri, is about 4.2 light years away.
What are stars within our galaxy?
The stars we see are all within the Milky Way galaxy, each potentially having its own planetary system.
What defines the large-scale structure of the universe?
Galaxies group together in clusters and superclusters, forming the large-scale structure of the universe.
How did the universe begin?
The universe began with the Big Bang.
What can we see with the naked eye in the night sky?
We can see stars in the Milky Way galaxy and two or three other galaxies with the naked eye.
