![]() ![]() Mercury is a rocky planet, one of the four “terrestrial planets” in our Solar System.Length of Year (Orbit): 87.97 Earth days.But this may have something to do with its incredible density, being composed primarily of rock and iron ore. And being equivalent in size to 0.38 Earths, it is just slightly larger than the Earth’s own Moon. Mercury is also the smallest planet in our Solar System, and is also smaller than its largest moon (Ganymede, which orbits Jupiter). ![]() Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington But despite its reputation for being sun-baked and molten, it is not the hottest planet in our Solar System (scroll down to find out who that dubious honor goes go!) Mercury, as imaged by the MESSENGER spacecraft, revealing parts of the never seen by human eyes. Mercury is the closest planet to our Sun, at just 58 million km (36 million miles) or 0.39 Astronomical Unit (AU) out. Included are quick facts and links so you can find out more about each planet. Here is a brief look at the eight planets in our Solar System. Having covered the basics of definition and classification, let’s get talking about those celestial bodies in our Solar System that are still classified as planets (sorry Pluto!). This subcategory includes Ceres, Pluto, Haumea, Makemake, and Eris. Later, in 2008, the IAU announced the subcategory of dwarf planets with trans-Neptunian orbits would be known as “plutoids.” Said the IAU, “Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighborhood around their orbit.” Scientists believe there may be dozens more dwarf planets awaiting discovery. This also reclassified the asteroid Ceres as a dwarf planet, too, and so the first five recognized dwarf planets are Ceres, Pluto, Eris, Makemake and Haumea. With much controversy then and since, Pluto was reclassified as a dwarf planet in 2006. It soon became clear that either they all had to be called planets or Pluto and bodies like it would have to be reclassified. With advances in equipment and techniques, astronomers knew that more objects like Pluto would very likely be discovered, and so the number of planets in our Solar System would start growing quickly. The change in the definition came after the discovery three bodies that were all similar to Pluto in terms of size and orbit, (Quaoar in 2002, Sedna in 2003, and Eris in 2005). This means that Pluto, which was considered to be the farthest planet since its discovery in 1930, now is classified as a dwarf planet. has “cleared the neighborhood” around its orbit.has sufficient mass to assume hydrostatic equilibrium (a nearly round shape),. ![]()
0 Comments
Leave a Reply. |