Astronomy Crossword

What is the the light that reflects off the surface of a star, moon, or planet?
In a solar system, what is it called when two stars, in orbit, are the farthest away from each other?
What is a theory that attempts to describe how the universe came to be?
A solar system, in which there is two two stars orbiting a barycenter
An object having a gravitational so strong, no matter or radiation can escape
A hypothetical type of matter that comes from dark energy?
An effect named after a person, in which the frequency of sound or light change as the source and the observer move toward or away from each other?
What equation is most to estimate the number of civilizations or intelligent life force in the universe?
The time at which the sun is at celestial equator and the length of day and night are the same
The velocity an object must have in order to escape the gravitational attraction of a planet
A shooting star
An object being only acted upon by gravity
A system of billions of stars held together by gravitational attraction
The force that keeps an object going straight until acted upon by an external force
A phase of the moon, in which there is no light reflecting?