Me brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula.5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects.8. describe the planets’ orbits around the sun.9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets.13. what causes the seasons?

Hey! I love space. So I have added all the answers for your questions

Explanation:      1.A blue shift is any decrease in wavelength (increase in energy), with a corresponding increase in frequency, of an electromagnetic wave; the opposite effect is referred to as red shift. In visible light, this shifts the color from the red end of the spectrum to the blue end.

2.This relic radiation is known as the cosmic microwave background radiation. The chemistry of life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the universe was only 10–17 million years old.  

3.  The observations of Edwin Hubble in 1929 suggested that distant galaxies were all apparently moving away from us, so that many scientists came to accept that the universe was expanding.

4.A nebula (Latin for 'cloud' or 'fog'; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. ... Most nebulae are of vast size; some are hundreds of light-years in diameter.

5.There are three main types of galaxies: Elliptical, Spiral, and Irregular. Two of these three types are further divided and classified into a system that is now known the tuning fork diagram.

6.There are 6 trillion miles in a light-year (approximately), so the distance we need to go is 6 trillion miles / light-year times 4 light-years, or 24 trillion miles. So, this trip would take 1.2 billion hours. There are 24 hours a day and 365.25 days per year, so this time in years is 137 thousand years. Alpha Centauri is 4.367 light years away from Earth.

7.Newton's law of universal gravitation states that two objects are attracted to each other by a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. ... For the force between two charges and separated by a distance.

8.The other objects are pulled into orbit around the Sun. ... There are eight planets in the Solar System. From closest to farthest from the Sun, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The first four planets are called terrestrial planets

9.The Asteroid Belt is a region between the inner planets and outer planets where thousands of asteroids are found orbiting around the Sun. More than 7000 asteroids have been discovered.

10.     Earth's rotation is the rotation of Planet Earth around its own axis. ... Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to other, distant, stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past.

11.A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. ... Most of the galaxies are 1,000 to 100,000 parsecs in diameter (approximately 3000 to 300,000 light years) and separated by distances on the order of millions of parsecs (or megaparsecs).  

12.Unlike the outer planets, which have many satellites, Mercury and Venus do not have moons, Earth has one, and Mars has two. Of course, the inner planets have shorter orbits around the Sun, and they all spin more slowly.  

13.How does the Sun cause the seasons? Seasons are caused by the Earth's revolution around the Sun, as well as the tilt of the Earth on its axis. The hemisphere receiving the most direct sunlight experiences spring and summer, while the other experiences autumn and winter.

There you go!

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

gag reflex, poor dentition, gum retraction

have a good day