AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Retrograde motion planets8/4/2023 ![]() ![]() The asteroid 514107 Kaʻepaokaʻawela has a retrograde orbit. Consequently, although both moons are traveling in an eastward (prograde) direction, they appear to be traveling in opposite directions when viewed from the surface of Mars due to their orbital periods in relation to the rotational period of the planet.Īpparent path of Mars in 2009–2010 relative to the constellation Cancer, showing its “opposition loop” or “retrograde loop” Both moons orbit Mars in an eastward (prograde) direction however, Deimos has an orbital period of 1.23 Martian sidereal days, making it supersynchronous, whereas Phobos has an orbital period of 0.31 Martian sidereal days, making it subsynchronous. This phenomenon also occurs on Mars, which has two natural satellites, Phobos and Deimos. As a result, it looks like the Moon is travelling in the opposite direction, otherwise known as apparent retrograde motion. ![]() This means that the Earth completes one sidereal rotation before the Moon is able to complete one orbit. The apparent westward motion of the Moon from the Earth’s surface is actually an artifact of it being in a supersynchronous orbit. In actual fact, the Moon orbits the Earth from west to east, as do the vast majority of manmade satellites such as the International Space Station. ![]() Day after day however, the Moon appears to move to the east with respect to the stars. When standing on the Earth looking up at the sky, it would appear that the Moon travels from east to west, just as the Sun and the stars do. The earliest recorded use of prograde was in the early 18th century, although the term is now less common. While the terms direct and prograde are equivalent in this context, the former is the traditional term in astronomy. Direct motion or prograde motion is motion in the same direction as other bodies. Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. ![]()
0 Comments
Read More
Leave a Reply. |