Its distance changes. It's not a perfectly circular orbit.

For most comets, the perihelion of their orbit lies outside the Earth's orbit.

In its elliptical orbit around the Sun the Earth moves at 30 kilometres a second.

The required speed is called orbital velocity, and it varies with the height of the orbit.

Fifty years later, as a tribute, the International Space Station, which is still up there tonight, synced its orbit with Gagarin's orbit, at the exact same time of day, and filmed it, so you can go online and you can watch over 100 minutes of what must have been an absolutely mesmerizing ride, possibly a lonely one, the first person to ever see such a thing.

It's as if some invisible rope is helping them hold on

Its spin axis will drift or precess. Gravity Probe B carried some super spherical gyros into Earth orbit to see what they would do.

The letters CST stand for Crew Space Transportation and the number 100 in the name stands for 100 km, the height of the Kármán line which defines the boundary of space.

So we move this Earth very close 30 kilometers outside and we notice it's perfectly fine orbiting around the black hole.

If you were to ask some people why we have seasons, they might say that maybe it's due to how far we are from the sun at different points in the year, different points in Earth's orbit.

Survey type NEO missions are dedicated to the detection, tracking (that is, orbit determination) and remote characterization (for example, determination of taxonomic type and surface albedo of NEOs).

Belatedly and somewhat reluctantly, EU leaders have now accepted that they need to deal pragmatically with Lukashenko if they want to promote reform in Belarus and shift the country from its tight orbit around Russia.

Milutin Milanković is known for his theory of ice ages, suggesting a relationship between the Earth's long term climate changes and periodic changes in its orbit, now known as Milankovitch cycles.

That policy achieved almost nothing, save for bolstering the country s authoritarian leader, President Aleksander Lukashenko. Belatedly and somewhat reluctantly, EU leaders have now accepted that they need to deal pragmatically with Lukashenko if they want to promote reform in Belarus and shift the country from its tight orbit around Russia.