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

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

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.

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.