A heavenly body which does not revolve in the same plane as other planets.
Answers
Answer:
EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!
The earliest stargazers noticed that the bright planets in our sky travel along the same path, more or less, as the sun and moon. We call that sky pathway the zodiac. Today, we know this sky path – this zodiac – results from the fact that the planets in our solar system orbit our sun more or less in a single plane. But today we also know thousands of other planets – called exoplanets – orbiting distant stars. Do they also orbit, more or less, in a single plane around their suns? If you stood on the surface of an exoplanet (assuming it had a solid surface to stand on), would you also see that system’s planets cross the sky in approximately the same path as the local star?
The answer is yes … and no. Keep reading.
Here’s the yes part of the answer, beginning with another astronomy definition; the Earth-sun plane is called the ecliptic. Most major planets in our solar system stay within 3 degrees of the ecliptic. Mercury is the exception; its orbit is inclined to the ecliptic by 7 degrees. The dwarf planet Pluto is a widely known exception to this rule. Its orbit is inclined to the ecliptic by more than 17 degrees.
It makes sense that most large planets in our solar system stay near the ecliptic plane. Our solar system is believed to be about 4 1/2 billion years old. It’s thought to have arisen from an amorphous cloud of gas and dust in space. The original cloud was spinning, and this spin caused it to flatten out into a disk shape. The sun and planets are believed to have formed out of this disk, which is why, today, the planets still orbit in a single plane around our sun.
