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All 8 questions. After you submit, each question shows the right answer and why. Back to the quick check
The Milky Way is the only galaxy there is.
What is the name of the galaxy we live in?
The Sun formed about 4.6 billion years ago and takes about 240 million years to orbit the centre of the Milky Way once. Roughly how many orbits has it completed?
Which list gives the main shapes astronomers use to describe galaxies?
What did Edwin Hubble use in 1923 to show that the Andromeda nebula lies outside the Milky Way?
Stars far from a spiral galaxy's centre orbit faster than the visible matter can explain. What do astronomers conclude, and why?
For a star on a circular orbit, v² = GM(r)/r. If a galaxy's rotation speed v stays roughly constant at large r, how must the enclosed mass M(r) behave, and what does that imply?
Which statement about dark matter is best supported by current evidence?
