What are tidal tails?

Jets of gas ejected from a supermassive black hole at a galaxy's center Long streams of stars drawn out from a galaxy by the gravitational tidal forces of a passing or merging galaxy Rings of gas left behind when a spiral galaxy loses its arms Clouds of gas ejected during a supernova explosion inside a galaxy

Why are the Antennae Galaxies (NGC 4038/4039) famous?

They are the two nearest galaxies to the Milky Way They are two spiral galaxies currently in the process of merging, with long tidal tails that look like insect antennae They are the brightest quasars visible from Earth They are two identical twin galaxies that formed from the same gas cloud

When two galaxies collide, why do their individual stars almost never physically hit each other?

The strong magnetic fields of both galaxies deflect the stars away from each other Stars move too slowly to collide during the brief period of the merger Stars are tiny compared to the enormous distances between them, so even in a collision the chance of two stars hitting is extremely small Dark matter absorbs the energy of any potential star-star collision

What happens to gas clouds when two galaxies collide, even if stars don't hit each other?

The gas clouds also pass right through each other without interacting The gas clouds are destroyed by the shock wave from the black hole collision The gas clouds do collide and compress, triggering intense star formation and creating a starburst galaxy The gas clouds are flung out of both galaxies and lost to intergalactic space

What type of galaxy do two merging spiral galaxies typically produce?

A larger, more magnificent spiral galaxy An elliptical galaxy, because the ordered rotational structure of the spirals is disrupted An irregular galaxy that will never develop a regular structure Two new spiral galaxies with different orientations

How fast are the Milky Way and the Andromeda Galaxy (M31) approaching each other?

At the speed of light At about 1 km/s — barely moving relative to each other At about 110 km/s At about 1,000,000 km/s

Approximately when will the Milky Way and Andromeda Galaxy collide?

In about 1 million years In about 4.5 billion years In about 100 billion years It will never happen — they are actually moving apart

What nickname do some astronomers give to the future merged galaxy of the Milky Way and Andromeda?

Andromilk Milkomeda Galacticus Prime The Grand Spiral

What will most likely happen to our solar system when the Milky Way and Andromeda collide?

It will be destroyed when two stars collide near our Sun It will almost certainly survive intact — the stars are too far apart to collide, but the solar system may end up in a new part of the merged galaxy It will be captured by the Andromeda Galaxy and orbit its center It will be ejected completely from both galaxies into intergalactic space

What is a starburst galaxy?

A galaxy where all the stars are exploding as supernovae simultaneously A galaxy forming new stars at an exceptionally high rate, often triggered by an interaction or merger with another galaxy A galaxy at the center of a cluster that emits powerful radio bursts A galaxy with more than 10 trillion stars