Galaxies
The observable universe is believed to be formed of 100 billion galaxies. A galaxy is a gravitationally bound group of stars, planets, stellar remnants, gas dust and dark matter. Earth and our Solar System are in the Milky Way galaxy, which is thought to contain 100 billion stars. The Milky way is part of the Local group, which also includes the Andromeda galaxy, our nearest neighbouring galaxy. Galaxies come in varying sizes and shapes, and can be categorised as spiral, elliptical or irregular galaxies.
What is a wandering star?
Nope, they haven’t been booted out of for bad behaviour.
Stunning new image of black hole at centre of our galaxy revealed
The groundbreaking image shows a strong magnetic field spiralling at the edge of Sagittarius A*.
How many galaxies are in the Universe? A lot more than you'd think
Our own galaxy, the Milky Way, has a diameter of 87,400 light-years.
If the universe is expanding, how are the Milky Way and Andromeda getting closer together?
Recent data from Hubble suggests that the Universe is expanding at a rate of around 73km per megaparsec (3.26 million light-years).
The Boötes void: Why the Universe has a mysterious hole 330 million light-years across
Space is full of holes.
Space telescope captures image of colliding galaxies
These two galaxies are being pulled together by gravity, and in a billion years they'll likely become one.
What is the average colour of the Universe?
Astrophysicist Dr Alastair Gunn explains how scientists calculated the Universe’s average hue – and what it looks like.
Galactic fireworks: New images of nearby galaxies
New photos of some stunning nearby galaxies containing new stars have just been released.
Sorry, the Milky Way isn't as cool as we thought it was
But a new discovery could be a game-changer, both for the history of our galaxy and the future of astronomy.
How do we know the Milky Way is a spiral galaxy?
The clues lie in the stars…
10-billion-year-old red giant stars help researchers understand how our galaxy evolved
The stars reveal information about the early Milky Way, before its collision with a satellite galaxy called Gaia-Enceladus around 10 billion years ago.
How do we calculate distances to other galaxies?
Asked by: Colin and Ann Dove
How can I see Betelgeuse?
See one of the brightest stars in the sky from September until April.
Astronomy for beginners | How can I see the Andromeda Galaxy?
Our galactic neighbour is visible all year from the UK, but clearest during the dark winter months.
How many stars are in the Milky Way?
Asked by: Sophie Wyatt
Ancient galaxies caught in supermassive black hole's spider web
The finding helps to understand how supermassive black holes formed and grew to their enormous sizes so quickly, researchers say.
Andromeda galaxy has a humongous halo of gas
Andromeda's halo extends approximately halfway to the Milky Way.
Ancient galaxy is quite chill, actually
The galaxy is 'surprisingly unchaotic, contradicting theories that all galaxies in the early Universe were turbulent and unstable'.
What colour is space?
Asked by: Jason Webb, Tennessee
What is the largest known celestial body?
Asked by: Dileep Bagnall, Lancashire
Hubble at 30 | What Hubble had to teach us about our home galaxy
The story of the stars is written across our Galaxy, and the Hubble Space Telescope has helped us read it.
How galaxies evolve
The Hubble Space Telescope was able to find 3,000 galaxies looking at an area of just one 24-millionth of the whole sky.
Star visible to naked eye reveals history of Milky Way Galaxy
The star, ν Indi, holds clues to the Milky Way's collision with the dwarf galaxy Gaia-Enceladus.
How far would we need to travel to leave our Galaxy?
It depends on whereabouts you want to get to; our vast Galaxy is thousands of light-years across, but for a decent vantage point you would need to travel much further.