How do you tell the difference between stars and planets?
Stars are big balls of fire that are much bigger than planets. Planets are hunks of debris left over from the formation of the star that revolve around stars, captured by their gravity. The only reason planets seem brighter in the sky is that planets are much closer. However, if the stars were brought closer (for instance, the sun, which is farther away than most some planets like Mars, Venus, and Mercury), they would light up the sky. You can tell the difference between stars and planets because stars turn over us in a uniform fashion, while planets do not seem to turn like the stars do over us. The reason for this is that while the Earth is turning and the stars are remaining still, the planets in our Solar System are also moving, causing them to seem to move out of sync with the other stars.
Observational Differences between Planets & Stars PLANETS The planets move relative to stars on celestial sphere The nearer and larger planets appear as disks in telescope The brighter planets do not “twinkle” The planets are always near the imaginary yearly path of the Sun on the celestial sphere (the ecliptic) STARS The relative positions of the stars are fixed on celestial sphere The stars appear as “points” of light, even through the telescope The stars appear to “twinkle” Stars can be anywhere on the celestial sphere
Stars twinkle because they give off a light(planets only reflect the sun’s light), and the light is sent through earth’s atmosphere which distorts the light waves. Venus, Jupiter, and Mars are the three planets that can be brighter than Sirius, then brightest star. Saturn and Mercury outshine many stars most of the year, and Uranus is very dim, hardly visible to the naked eye. Neptune cannot be seen without the aid of binoculars, and the same is true for Pluto. Dwarf planet Ceres can occasionally and very rarely get bright enough to be seen without optical aid. Also, planets move against the background stars. This is not extremely obvious to the eye, but when seen through a telescope, the planets, especially the closer ones will move out of the field of view in minutes, or even seconds. Finally, when viewed through a modest sized telescope, planets all show a disk, even far off Neptune. Stars will only appear as an unsteady orb of light. Hope this helps.
