What is an angular diameter?
The angle diameter of the object applies to the size that seems to be. It is usually defined as an angle, usually divided by its distance in the ratio to the actual size of the object. The angular distance from one side of something to the other is often used to measure the size of objects in the night sky. The circle is 360 ° around, while the distance over the sky equals half a circle or 180 °. Objects in space are usually measured using ARC second, which equals 1/3 600. 1 °.
Another measurement often used with an angular diameter is a radian that is 180 ° divided by pi, or 3.14 times the diameter of the circle. The angular diameter can therefore be determined by the fact that the answer to this calculation, which is 206 265 and divides it by the actual distance. The obvious size of the object may be similar to others that can be much larger, but often it is a comparative distance from the ground that make them look the same.
The sun and the moon are usually the same in the angular diameter when it is visible from the ground, although one is about 400 times wider than the other. Seems to beThey are about ½ ° opposite the ground observers. While 1/3 600. 1 ° is an arch for a second, the arc minute is 1/60 of 1 °. People with normal visual acuity can see something that has an arc diameter; This is generally similar to viewing a coin of $ 0.01 (USD) from $ 226 (about 70 meters).
Astronomers often use binoculars that can clarify objects that are on the second arch. The strongest telescopes can be used to view objects that are up to 0.1 seconds wide. Such an apparent diameter can be used in the calculation along with the known distance to calculate how wide it is. Similar calculations are often used to compare the size of the Sun with other stars and to determine the size of other galaxies, nebulae, and the objects that can be seen in the universe.
Angle diameter can be estimated by human hand. By holding the arm directly out, the pinky finger usually covers 1 ° night sky. In general, the fist is about 10 ° across relation to objects such as stars and galaxies. AstronomersThey calculated the angular diameter for the planets in the solar system and many other known objects in the sky.