astronomical distance ..how do they do it?

Question

on a tv show tonight they said 150 million kilometers and 93 million miles=1AU

how did they figure that out ?
is there some sort of scale ?

Answer 1

The first way this was determined was by solar parallax, which can be found during a solar eclipse. Basically, you compare the diameter of the umbra (the area of total eclipse) to the penumbra (area of partial eclipse). Since the size and distance of the Moon is known, the distance to the Sun is the only unknown in the equation.

More recently, we determine the scale of the solar system by bouncing radar off the planets. Since you can determine the *relative* size of their orbits (compared to Earth's orbit) by simple observation, knowing the absolute distance to, say, Venus, also gives you all the other solar system distances as well.

Answer 2

93 million miles = 1 AU , or Astronomical Unit

This also is the distance between the Earth and the Sun, and where this unit originated from.

Answer 3

The first reliable value came from studying transits of Venus. Expeditions were sent out to widely separated places and getting accurate timings of Venus crossing in front of the sun. By analysing the timings, and knowing where they were taken, it was possible to work out the AU. James Gregory came up with the idea, but it was Edmund Halley, of comet fame, who was the driving force behind what became the first international science project.

Captain Cook was probably the most famous person involved (at least in the UK) but there were many others with amazing tales to tell - look up Guillaume Joseph Hyacinthe Jean-Baptiste
Le Gentil de la Galaisiere, who spent 9 years away from home and travelled almost 70,000 miles without managing to get a single observation. When he finaly did get home he found he'd lost his job and his wife and had been declared dead!

Total eclipses are not used.

Answer 4

see: http://en.wikipedia.org/wiki/Astronomical_unit#The_distance


Originally, the AU was defined as the length of the semimajor axis of the Earth's elliptical orbit. In 1976, the International Astronomical Union revised the definition of the AU for greater precision, defining it as the distance from the centre of the Sun at which a particle of negligible mass, in an unperturbed circular orbit, would have an orbital period of 365.2568983 days (one Gaussian year). More accurately, it is the distance at which the heliocentric gravitational constant (the product GM☉) is equal to (0.017 202 093 95)² AU³/d².

Answer 5

AU stands for Astronomical Unit and is the distance that the Earth is from the Sun

Answer 6

Well it's an average distance because the Earth's orbit is elliptical, so the distance from the Earth to the Sun does NOT remain constant. It varies. So one AU is the average distance between the Earth and the Sun.

Answer 7

The astronomical unit is simply the average radius of the earth's orbit around the sun. The radius is determined by observations of various planets, and use of Kepler's laws.

Answer 8

1AU = Average distance between the earth and sun!
Basic geometry was use to figure this out.

Answer 9

light is another way of measuring distance too. many new planets will be discovered this way