How did the ancient astonomers know the planets were different from the stars?
The planets move in their own trajectory which is different than the stars in the background. All the stars appear to circle the North star.
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The greek Aristotle writted a theorie of the universe based on what Greeks considered geometrical perfect bodies; 5 bodies, then 5 planets: Mercury, Venus, Mars, Jupiter, and …Saturn. Greeks do not have considered the Earth a planet.The do not have known about Uranus, Neptune, and Pluton.Today, have been discovered far objects with equal or suspected bigger size than Pluton (like Quaoar), and Pluton is not more considered a planet.
2 things separate them visually. First, planets move. You won't see this in one night, but if you watch the object from night to night, you will see that it has moved a sho…rt distance each time. Okay, stars move too - but you would have to watch for thousands of years just to see them move much at all. Secondly, depending on which planet and how good your telescope is, Planets can be magnified into a circle - you can see breadth. Even the most powerful telescopes only see stars as a bright pinprick of light. That's because they are millions of times further away.
\n. \n. \nAncient astronomers can tell the difference the same way you can tell now - the planets move, while the stars stay in the same patterns. The word "planet" comes f…rom the Greek word for "wanderer". The 'planets' were the lights in the sky that moved. Originally the Greeks included the Sun and Moon as planets, because they were light's that moved through the sky.\nAlso, the closer and bigger planets, Jupiter, Mars & Venus are also MUCH brighter than stars. The smaller planets and the ones that are far, far away (Mercury & Saturn) are also bright - but not much brighter than the brightest stars in the sky. They also all travel in the same narrow path in the sky - the ecliptic. It's the same path the sun & moon follow in the sky through the months & year.\n. \nThese 7 lights were visible in the sky without telescopes - Sun, Moon, Mars, Mercury, Jupiter, Venus & Saturn - which is how we got our 7 days of the week.
Earth. An Astronomical Unit is a unit of distance measure defined as the mean (average) distance between the Earth and the Sun; thus, the earth orbits the sun at a distance… of 1 Astronomical Unit. The Astronomical Unit was invented to make it easier to think of astronomical distances within the Solar System ... it is easier to get a feel for how close the planets and other bodies in the solar system are close to the sun in terms of Astronomical Units (AUs) than millions of kilometers: Mercury at 0.4 AU versus 50 million kilometers, Venus at 0.7 AU versus 108 million kilometers, etc.
There are two tools that astronomers use to determine that a far-off star has planets. 1. Occultation: When a planet passes in between the Earth and another star, it is cal…led an "occultation", from the Latin word "occult" or "hidden". The light measurement from the star will be slightly decreased when a planet passes in front of the star. Think of it as a very par away eclipse. This only works for very large planets. 2. Gravitational "wobble": A large planet attracts a star as much as the star attracts the planet, and they both orbit their joint center of gravity. Because the star is so much more massive than the planet, the star only wobbles very slightly, but over long periods it is possible to notice the differences.
In a very few recent cases we have directly observed the planets. Most exoplanets (planets orbiting other stars) are detected through periodic wobbles in the light of the star… as the planet makes its way around. That may change this month with the launch of the Kepler satellite later today. The third way to detect planets is by their transits. If the distant planet crosses in front of the star and us, the star light dims in a characteristic manner. Kepler will observe thousands and thousands of stars for transits.
What an excellent question. It appears you already realize that if you are talking about stars other than our sun, you are talking about stars that are many lightyears away fr…om us, and not even powerful telescopes will easily detect planets orbiting around them. One thing that astronomers can sometimes detect is the slight wobble of distant stars as planets orbit around them. You might not realize that suns would move as a result of a planet's orbit. Imagine you and a friend holding on to the ends of a rope. If you begin to move in a circle, you will each feel the centripedal force pushing you outward. Neither of you would be able to stand perfectly still while the other circled with the rope.. Another thing that astronomers can detect using very sensitive equipment is the slight reduction in brightness of a star when a planet's orbit brings the planet between us and its star. If this reduction in brightness is regular enough, it may be an indication that there is a planet in orbit.
There were no telescopes prior to 1608, so no "ancient" astronomers ever used one.
a star is a ball hydrogen gas
Planets can cause the star to have a very slight wobble or shift in normal path. This is picked up by a spectrogram. Some planetary systems actually have dust clouds around th…e star.
In astronomy, Aries (latin for 'ram') is a constellation recognizedboth in ancient and modern times, visible in the northernhemisphere. This is not to be confused with Ares, t…he Greek god ofwar, whose Roman equivalent is Mars (after which the planet isnamed). The moons of Mars, Phobos and Deimos, are named after sonsof Ares (Mars) and Aphrodite (Venus). In addition, there is anastrological reference to Aries (again, the symbol of the ram)which is associated with both Mars and Pluto - (in astrology, notthe planet).
space is made up of men and maggots who are like wolves and dragons, so space is men on dragons throwing wolves at maggots... your welcome...
Astronomers use the unit of measure "Light Years" to calculate the distance between pretty much anything in the Universe.
Almost nothing was different, except our understanding of things. The stars have been shining for millions or billions of years; all the planets have been pretty much just whe…re they are for about 4 billion years or more. "Ancient" times in our human history is anything more than 2000 years ago.
Mercury, Venus, Earth, Mars, Jupiter, and Saturn were.
Planet means "wanderer". The planets moved against the background of the fixed stars.