Compared with a completely still universal reference point, how fast am I moving and in which direction?
Chris Daniel
Glan Conwy, UK
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Right now, you are probably stationary relative to your surroundings. But Earth is on its daily rotation about its axis, so, relative to a point in space just above you, east at up to 1670 kilometres per hour, depending on how close you are to the equator. Earth is also orbiting the sun at around 107,000 km/h in an anticlockwise direction as viewed from the North Pole.
Meanwhile, the stars in our neighbourhood of the galaxy are all moving round the Milky Way at slightly different speeds relative to one another: is currently moving at 70,000 km/h towards the star Vega. But at the same time, we are following an orbit across around the centre of the galaxy at speeds of about 828,000 km/h, taking around 225 million years. The is tilted about 60 degrees to the plane of the galaxy.
Our total speed in the universe is unimaginably fast, but we do know the direction we are heading in
The Milky Way is also moving through the universe, but it isn鈥檛 possible to measure its speed against a stationary point because the universe is expanding. However, our speed and direction can be deduced by observing the red and blue shift in the cosmic microwave background radiation, the remnants of the big bang. Our galaxy has been shown to be travelling at 390,000 km/h towards the Andromeda galaxy, our nearest neighbour in the local group of galaxies, which is part of the bigger Virgo Supercluster. Together, we are moving at 2.2 million km/h towards a point called The Great Attractor in the centre of the even larger Laniakea Supercluster.
Our total speed in the universe is unimaginably fast, but we do know the direction we are heading in 鈥� at least for the next few billion years.
Eric Kvaalen
Les Essarts-le-Roi, France
There is no such thing as a completely still universal reference point. That idea may have held for most of history, but it has been eroded bit by bit.
At first, people thought Earth was immovable, but some of the ancient Greeks believed it was rotating, and Aristarchus of Samos even proposed that it travelled around the sun. This wasn鈥檛 accepted until after Nicolaus Copernicus in the early 16th century.
Newtonian physics showed that even the sun moves, jostled by the pull of the planets. In Newtonian physics, there is no notion of 鈥渟tationary鈥�. General relativity maintains that all free-falling objects are equally entitled to be called stationary, and obviously they move, one with respect to another.
You could take the centre of gravity of the Milky Way as a sort of stand-in for a stationary point. With respect to that, we are moving at around 230 kilometres per second in the direction of the star Deneb in Cygnus.
Alternatively, we could use the cosmic microwave background radiation as a standard. In that case, we are moving at around 370 km/s in the direction of the constellation Leo.
David Muir
Edinburgh, UK
Earth rotates on its axis once every 23 hours, 56 minutes and 4 seconds, and its circumference at the equator is around 40,000 kilometres. This means if you are sat on the equator, you are moving at over 1600 km/h due to Earth鈥檚 rotation. Your speed decreases if you go north or south.
Examples of spin speeds as you go north are: Paris = 1096 km/h; London = 1040 km/h; Edinburgh = 933 km/h; Reykjavik = 732 km/h; Qaanaaq in Greenland = 362 km/h. If you were sat at the North Pole, you would be stationary but rotating once a day. You and your head would be literally spinning, but slowly.
Michael Ham
Matthews, North Carolina, US
Today, I walked a mile in 15 minutes. I鈥檓 tired! As I was doing that, Earth turned 420 km on its axis as it moved 2670 km in its journey around the sun and the solar system danced for 16,000 km within our galactic arm and the Milky Way turned 190,000 km around its centre as our galaxy flew 540,000 km through the ether, and always in a counterclockwise direction.
Today, I travelled 749,090 km in 15 minutes! I鈥檓 really dizzy and really, really tired.
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