Why are celestial bodies called celestial bodies

Astronomy introduction


Meteors, also called falling stars, are luminous phenomena within the earth's atmosphere. They arise when relatively small bodies with a mass of a few grams to several (100) kilograms reach the Earth's area of ​​attraction and hit the air molecules at high speeds. These objects are called meteoroids. When they hit the air molecules at high speeds, friction occurs, which causes the metoroids to heat up. This stimulates the air molecules to glow, which leads to the formation of the light trail. However, the hot bodies themselves contribute little to the luminous appearance. Most metoroids burn up when they enter the atmosphere. In the case of larger bodies, a remnant of it can fall to the surface of the earth and strike there. The rest of the body is then called a meteorite. It usually consists of stone, iron or nickel. Meteorites are therefore valuable evidence of the chemical composition of other celestial bodies in the solar system. The point of impact is called a meteorite crater.

Meteors occur increasingly when our earth crosses the orbit of so-called meteor streams. Such meteor streams are mostly the orbits of former or still existing comets, which have partially dissolved into individual parts when they approached the sun. When passing through such a meteor shower, e.g. the Perseids or the Leonids, one can often observe up to \ (100 \) falling stars in one hour.

You can find detailed information about meteorites on the page about meteorites of the Mineralogical Museum of the University of Würzburg.

The moon

The moon is the only natural celestial body that has been entered by humans (apart from earth). All planets (except Mercury and Venus) have several moons, but Earth only has one. Galileo GALILEI recognized mountains, craters and seas on the moon (although these are not filled with liquid).

The distance to the moon can be determined by triangulation or by measuring the time of flight of a laser signal. Due to the elliptical orbit, the distance fluctuates between \ (356410 \, \ rm {km} \) and \ (406770 \, \ rm {km} \); however, the deviation from the circular path is relatively small.

The diameter of the moon can easily be estimated if the distance to the moon is known: The nail of the little finger (\ (1 \, \ rm {cm} \)) on the outstretched arm at a \ (1 \, \ rm {m} \) distance is roughly hidden the full moon disc. Using the direct proportionality, one can determine the moon diameter from this:
\ (\ rm {Moon diameter = moon distance \ cdot finger width: distance \ of the \ finger \ from the \ eye} \)
\ (\ rm {Moon diameter = moon distance} \ cdot (1 \, \ rm {cm}: 100 \, \ rm {cm}) \), i.e. one hundredth of the moon distance
The correct value for the moon diameter is \ (3476 \, \ rm {km} \).

The synodic period of revolution (from the point of view of the rotating earth) is \ (T _ {\ mathrm {syn, moon}} = 29 {,} 5 \, \ rm {d} \).
The sidereal orbital period (from the point of view of the non-rotating star background) is \ (T _ {\ mathrm {sid, moon}} = 27 {,} 3 \, \ rm {d} \).

Here you can find exactly what the synodic and the sidereal period are.

The moon stands approx. 13 ^ f further east every day, so it rises approx. 50 minutes later every day.
A: New moon (You cannot see the illuminated side of the earth! From the night side of the moon you can see the illuminated earth side four times larger than the moon. You can therefore see the night part of the moon, which is dimly lit by the earth)
B: Increasing, sickle curved to the right (German Z)
C: Crescent: shadow border is diameter

Artificial satellites

Larger earth satellites can be observed with the naked eye as points of light moving across the night sky. The ISS space station, the largest artificial object in Earth orbit, achieves one and a half times the apparent brightness of the brightest stars. In contrast to an airplane, a satellite does not have any flashing colored lights. However, in some of the objects, the brightness changes due to the rotating or tumbling movement.