Universe Crossword

All of time and space and its contents
A collection of millions and trillions of stars composed of dust and dark matter, all held together by gravity
Is the process by which multiple nuclei join together to form a heavier nucleus.
A luminous ball of gas, mostly hydrogen and helium, held together by its own gravity.
Interstellar clouds of dust, hydrogen, helium and other ionized gases which can give rise to new stars
A spiral galaxy in which we live in
A galaxy with long arms winding toward a bright bulge at the center
A type of galaxy having an approximately oval shape and a smooth, nearly featureless brightness profile.
A galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.
A leading explanation about how the universe began.