Comets

Comets were already known to primitive man. The brightest ones are unlike any other object in the sky. They look like spots of light, often blurred, leaving a trail or "tail". This makes them attractive and surrounds them with magic and mystery. Comets are small, fragile bodies, irregular in shape, made of a mixture of hard substances and frozen gases. The orbit of comets is very eccentric; during perihelion they come quite close to the Sun, but on their way to aphelion, they can move far beyond Neptune. When a comet approaches the Sun and heats up, the gases evaporate, releasing solid particles and forming the tail. As it moves away, it cools, the gases freeze and the tail disappears.

Thus, only the rocky core remains. It is believed that there are asteroids that are comet nuclei. There are comets with short orbital periods and others with long ones. Some do not exceed the orbit of Jupiter and others go so far away that they reach the limits of the Solar System.

Kites, "dirty snowballs"

Comets are composed of a mixture of nonvolatile grains and frozen gases. They have highly elliptical orbits that take them very close to the Sun and back into deep space, often beyond the orbit of Neptune. Comet structures are diverse and dynamic, but all form a surrounding cloud of diffuse material ("tail") that generally grows in size and brightness as the comet approaches the Sun. As comets approach the Sun, they develop enormous tails that extend millions of kilometers from the head, away from the Sun. When they are far from the Sun, the nucleus is very cold and its material is frozen. In this state, comets are sometimes called "dirty icebergs" or "dirty snowballs."

When a comet approaches the Sun, a few ua (astronomic units) of the Sun, the surface of the core begins to heat up and the volatiles evaporate. The evaporated molecules break off and drag small solid particles forming the comet's tail of gas and dust. When the core is frozen, it can only be seen due to reflected sunlight, appearing like an ordinary asteroid.

The observation of a comet turns out to be a rather special event for observers on Earth, along with many others. celestial phenomena that are within our reach, both with the naked eye and with optical instruments.