The nine planets in this solar system somewhat align once every 500 years and are grouped within 30 degrees every one to three alignments. When astrologers describe the planets as being aligned, they do not necessarily mean that all of the planets line up on a perfectly straight line. The last alignment within 30 degrees occurred in 561 B.C., and the next alignment within 30 degrees takes place in 2854.
All of the planets are within the exact same quadrant – within about 90 degrees of each other – about once every 200 years, but they line up more loosely on a more frequent basis. There is never an exact alignment from the vantage point of the sun because of the differences between the axial tilts of the planets in this solar system.Learn More
The nine planets in the solar system range in size from approximately 3,000 to 140,000 kilometers in diameter. Ranked from smallest to largest the planets are Pluto, Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn and Jupiter.Full Answer >
The nine planets in order are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and, if it's still considered the ninth planet, Pluto. However, not only has Pluto been demoted to a dwarf planet by some astronomers, but its orbit is so eccentric that there are times when it's closer to the sun than Neptune.Full Answer >
In this solar system, Mercury and Venus have no moons. Mercury is the smallest planet in the solar system and only slightly larger than Earth's moon. It is the closest planet to the Sun. Venus is the second closest planet to the Sun and is slightly smaller than Earth.Full Answer >
Six of the eight planets in the solar system are known to have moons. Mercury and Venus lack orbiting bodies of any significant size. Earth has one moon, Mars has two, and the gas giants have several moons each.Full Answer >