orbital period

astronomy

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July 15, 2026

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In astronomy, an orbital period is the time it takes for a celestial body to complete one orbit around another. This concept is fundamental to understanding planetary motion, as described by Johannes Kepler's laws. For instance, the Moon's sidereal period, the time to orbit Earth relative to the stars, is about 27.3 days, while its synodic period, the time between phases like full moon to full moon, is about 29.5 days. Planets also have orbital periods; Jupiter's sidereal period is approximately 11.86 Earth years. These periods are crucial for calculating orbital parameters and understanding gravitational influences within solar systems.1234

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Neptune
Basic astronomical data
Having an orbital period of 164.79 years, Neptune has circled the Sun only once since its discovery in September 1846. Consequently, astronomers expect to be making refinements in calculating its orbital size and shape well into the 21st century. Voyager 2’s encounter with Neptune resulted in a…
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Having an orbital period of 164.79 years, Neptune has circled the Sun only once since its discovery in September 1846. Consequently, astronomers expect to be making refinements in calculating its orbital size and shape well into the 21st century. Voyager 2’s encounter with Neptune resulted in a…
Read More

spaceflight
Earth orbit
…complete revolution is called the orbital period. At 200 km this is about 90 minutes. The orbital period increases with altitude for two reasons. First, as the altitude increases, Earth’s gravity decreases, so the orbital velocity needed to balance it decreases. Second, the spacecraft has to travel farther to circle…
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…complete revolution is called the orbital period. At 200 km this is about 90 minutes. The orbital period increases with altitude for two reasons. First, as the altitude increases, Earth’s gravity decreases, so the orbital velocity needed to balance it decreases. Second, the spacecraft has to travel farther to circle…
Read More