Quiz, myth or fact, and the galactic odometer

1. 1 What kind of galaxy is the Milky Way?

   EllipticalBarred spiralIrregularA ring
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   Barred spiral. It is a large barred spiral galaxy. NASA Imagine

2. 2 Where does the word ‘galaxy’ come from?

   Latin for ‘star road’Greek for ‘milky’Old Norse for ‘river’Arabic for ‘dust’
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   Greek for ‘milky’. Our word ‘galaxy’ comes from the Greek ‘galaxias’, meaning ‘milky’. Royal Observatory

3. 3 About how far is the Sun from the centre of the Milky Way?

   2,600 light-years26,000 light-years260,000 light-years2.6 million light-years
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   26,000 light-years. The Sun is about 26,000 light-years from the centre, roughly halfway between the centre and the outskirts. ESA, guide

4. 4 Which small arm is the Sun near?

   The Perseus ArmThe Orion Arm, or Orion SpurThe Norma ArmThe Scutum-Centaurus Arm
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   The Orion Arm, or Orion Spur. The Sun lies near a small, partial arm called the Orion Arm, or Orion Spur, between the Sagittarius and Perseus arms. NASA, Milky Way map

5. 5 About how long does one trip round the galaxy take, says the Royal Observatory?

   230 thousand years2.3 million years230 million years23 billion years
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   230 million years. Royal Observatory: one orbit takes about 230 million years, and is called a galactic year. Royal Observatory

6. 6 What is the black hole at the centre called?

   Cygnus X-1Sagittarius A*M87*Andromeda
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   Sagittarius A*. At the heart of the bulge sits the supermassive black hole Sagittarius A*, with the mass of four million Suns. Royal Observatory

7. 7 What is our nearest large neighbour galaxy?

   AndromedaTriangulumThe Large Magellanic CloudThe Sagittarius dwarf
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   Andromeda. Our nearest large neighbour, the Andromeda Galaxy, is 2.5 million light-years away. Royal Observatory

8. 8 How many galaxies are in the Local Group, says NASA?

   FiveOver 50About 5,000About 2 trillion
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   Over 50. The Milky Way sits in a neighbourhood of more than 50 other galaxies called the Local Group. NASA, galaxies

9. 9 In which year did Galileo report that the Milky Way is made of stars?

   1066161019172005
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   1610. In his 1610 book Sidereus Nuncius, Galileo reported that through a telescope parts of the Milky Way resolved into many stars. Library of Congress

10. 10 What did NASA’s Spitzer telescope prove in 2005?

    The central barThe black holeAndromeda’s distanceThe Milky Way’s age
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    The central bar. The bar wasn’t proven until 2005, when a team used NASA’s Spitzer Space Telescope to survey stars at the centre in infrared light, which gets through the dust. Royal Observatory

11. 11 What did the 2025 study find about a collision with Andromeda in the next 10 billion years?

    It is certainAbout a 50-50 chanceNo chance at allIt already happened
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    About a 50-50 chance. In 2025 a new study using Hubble and Gaia data found only about a 50-50 chance of the two galaxies colliding in the next 10 billion years. NASA, 2025

12. 12 How many official dark sky sites does the Isle of Man have?

    71226100
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    26. The Isle of Man now has 26 official dark sky sites. Visit Isle of Man

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1. 1 The Sun sits about halfway out from the centre of the Milky Way.

   MythFact
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   Fact. NASA: Earth sits along one of the spiral arms, about halfway from the centre. NASA, galaxies

2. 2 With your eyes alone you can see the colours from Milky Way photos.

   MythFact
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   Myth. With your eyes alone you won’t see the colours in photos: the Milky Way looks like fuzzy, colourless patches of light in a rough strip. Royal Observatory, naked eye

3. 3 Every star you can see at night is in the Milky Way.

   MythFact
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   Fact. Every star you can see in the night sky is part of our own Milky Way. NASA Imagine

4. 4 Spiral arms keep the same stars for ever.

   MythFact
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   Myth. Arms don’t keep the same stars. ESA’s Jos de Bruijne compares them to traffic jams: stars leave at the front while more pile up at the back. ESA, Gaia

5. 5 There are photos of the whole Milky Way taken from outside it.

   MythFact
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   Myth. No spacecraft has gone far enough to photograph the Milky Way from outside, so every picture of the whole galaxy is an artist’s impression or a data map. Royal Observatory

6. 6 Andromeda is getting closer to us.

   MythFact
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   Fact. Andromeda is getting about 110 km (70 miles) closer to us every second. Royal Observatory

7. 7 Most of the Milky Way’s mass is dark matter.

   MythFact
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   Fact. A roughly spherical halo of dark matter about a million light-years wide provides 90% of the galaxy’s total mass. Royal Observatory

8. 8 The Milky Way is the only galaxy.

   MythFact
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   Myth. Based on the deepest images so far, ours is one of about 2 trillion galaxies in the observable universe. NASA, how big

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