Everything in the universe moves, either at big or small speeds, and there are places too which require a certain speed to escape from them, like in it the case of the Earth. This speed is called escape velocity, and it is the speed that must reach the object or the rocket to leave the gravitational field of the planet or the star. In this article we’ll see at which speeds orbit the different celestial bodies or which escape velocities are escape of them.
We’ll start with a planet that we know very well: the Earth, our planet.
The Earth is not the most massive celestial body of our universe, but, however, it needs an elevated escape velocity, meaning, an elevated speed to leave its gravitational field: 40 000 km/h. At the same time, the Earth turns around the Sun with a medium speed of 29,8 km/s. It arrives at a maximum speed at the perihelion of 30,75 km/s, and at a minimum speed of 28,76 km/s at the aphelion.
The Sun requires a big escape velocity too, and, as it is to assume, it is bigger than the Earth one’s. In this case, the escape velocity of the Sun is of 42,04 km/s, what it comes to be an escape velocity 4 times bigger than the Earth’s.
At the same time, all the solar system turns around our galactic centre. This movement is done at 220 km/s. With this speed, the Sun, accompanied by the rest of planets, give a revolution to the Milky Way in 250 millions of years. With this last data, we calculate that, since he was born, the Sun has done about 20 laps at the Milky Way.
This movements aren’t the unique ones in the universe, our galaxy also moves. One of the movements of the Milky Way is its approximation to the galaxy of Andromeda, our nearby galaxy, at 400 000 km/h. It also turns around the Local Group, the ensemble of the closest galaxies to us.
The Local Group also moves, turning around the Virgo supercumulus, to which we belong.
All the cumulus and supercumulus of our universe have a trajectory to a precise place: the supercumulus of Laniakea. Around the 70th, a group of scientists discovered that, our galaxy and the nearby ones were attracted towards a same place, at an enormous speed: 600 km/s. This place was baptized as the Big Attractor. This movement was due to the supercumulus of Laniakea, which includes more than one hundred thousand galaxies, including the Local Group ones.
All things we’ve seen are moving, the majority rapidly for us, but there is a speed which is even bigger: the speed of light, the biggest speed of the universe and that is impossible to beat. The light is the fastest thing that we know: 300 000 km/s, or, exactly, 299 792,458 km/s.
Previously I’ve talked about the escape velocity of the Earth and the Sun, which requires that this speed must be quite big. But what would be the escape velocity of a dark hole, the most massive celestial body?
To leave the gravitational field of a dark hole, we would need an enormous speed. This speed is greater than 300 000 km/s. Yes, a bigger speed than the light’s, and, like I’ve said that nothing can beat the light’s speed, which is of about 300 000 km/s, it means that nothing can run away from a dark hole when you are very close to it.