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Thus the orbital period in low orbit depends only on the density of the central body, regardless of its size. So, for the Earth as the central body (or any other spherically symmetric body with the same mean density, about 5,515 kg/m 3, [2] e.g. Mercury with 5,427 kg/m 3 and Venus with 5,243 kg/m 3) we get: T = 1.41 hours
Mercury has an orbital speed of 47.4 km/s (29.5 mi/s), whereas Earth's orbital speed is 29.8 km/s (18.5 mi/s). [112] Therefore, the spacecraft must make a larger change in velocity ( delta-v ) to get to Mercury and then enter orbit, [ 187 ] as compared to the delta-v required for, say, Mars planetary missions .
According to the conservation of angular momentum, ω 1 changes with the radius r =; where m and L 1 are the first particle's mass and angular momentum, respectively, both of which are constant. Hence, ω 1 is constant only if the radius r is constant, i.e., when the orbit is a circle. However, in that case, the orbit does not change as it ...
Mercury – smallest and innermost planet in the Solar System. Its orbital period (about 88 Earth days) is less than any other planet in the Solar System. Seen from Earth, it appears to move around its orbit in about 116 days. It has no known natural satellites. It is named after the Roman deity Mercury, the messenger to the gods.
Mercury, the closest planet to the Sun at 0.4 astronomical units (AU), takes 88 days for an orbit, but the smallest known orbits of exoplanets have orbital periods of only a few hours, see Ultra-short period planet. The Kepler-11 system has five of its planets in smaller orbits than Mercury's.
The orbital radius and angular velocity of the planet in the elliptical orbit will vary. This is shown in the animation: the planet travels faster when closer to the Sun, then slower when farther from the Sun. Kepler's second law states that the blue sector has constant area.
For example, to view the eccentricity of the planet Mercury (e = 0.2056), one must simply calculate the inverse sine to find the projection angle of 11.86 degrees. Then, tilting any circular object by that angle, the apparent ellipse of that object projected to the viewer's eye will be of the same eccentricity.
The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the orbital plane and the plane of reference, normally stated in degrees. For a satellite orbiting a planet, the plane of reference is usually the plane containing the planet's equator.