Night sky: how to identify comets and asteroids?

People have been fascinated by the night sky since a time when stars did not have to compete with other light sources. This admiration, which has become an ancient culture, has continued its existence over time with technological developments, and what used to be respect turned into curiosity.

Events such as the last solar eclipse on April 8, observed today only in the northern hemisphere, attract crowds from around the world. However, a wide variety of celestial bodies — Asteroids, comets, meteors, meteors, and meteors can sometimes confuse backyard astronomers’ understanding..

Therefore we will explain below main differences between asteroids and comets, Both are officially called near-Earth objects (NEOs) because they can eventually pass through our planet’s orbital neighborhood and travel in orbits that take them an average of 195 million kilometers from the Sun.

Comets x asteroids: how to define?

Comets have left their mark on human history from the beginning, being viewed as celestial events and often interpreted as omens of important events or messages from the gods. For this reason, Its appearance in the sky has always caused great admiration, but also fear and suspicion among ancient civilizations.

Asteroids were completely unknown, until the first was officially discovered on January 1, 1801, by monk, mathematician and astronomer Giuseppe Piazzi.

Realizing that the object is too small to be a star and is moving too fast relative to the background constellations, It is named after the Greek word “asteroeidís” (star-like). In fact, the object observed by the Italians became neither a star nor an asteroid: it was Ceres, which is now considered a dwarf planet.

comets

Comets are very similar in size to small and medium-sized asteroids, but are more visible even if they do not come very close to Earth. What sets them apart is their “hair” (comets in Greece).

Comets are mostly composed of ice mixed with some dust and possibly rock fragments. As they approach the Sun, their icy outer layers warm above freezing. Then, ice (consisting of water, carbon dioxide, methane and ammonia) changes from a solid to a gas (sublimation).

These gases released into space form a diffuse cloud (coma) around the comet’s nucleus, a bright sphere that can extend up to thousands of kilometers. The release of gases also drives out large amounts of dust particles and debris from the ice. It forms the bright tail (or mane) common to most comets.

asteroids

Asteroids, sometimes confused with comets and sometimes called minor planets, are rocky, non-atmospheric fragments left over from the initial formation of our solar system 4.6 billion years ago. Counted in millions, They cluster in the so-called asteroid belt, a region located between the orbits of Mars and Jupiter.

The current number of these objects known to NASA is at least 1,351,400, according to the space agency’s website. The sizes of these stones vary. From bodies less than 10 meters long to giants like Vesta with a diameter of 530 kilometers. But if we add up the mass of all of them, it is smaller than the Earth’s Moon.

However, since they are just pieces of rock, albeit sometimes a little dust, they do not have the ability to emit their own light, nor do they have enough ice to imitate a powerful mane. However, to say this; if an object contains ice it is a comet; and if not, it’s an asteroid, that’s an oversimplification nature has already taken care of the complication.

3200 Phaeton: asteroid or comet?

When astronomers discovered the asteroid Phaeton in 1983, they realized that its orbit corresponded to that of Geminid meteors and positioned this object as the source of the traditional annual meteor shower. Despite, This is a characteristic of comets that leave a trail of debris behind.

NASA’s Solar-Terrestrial Relations Observatory (STEREO) further complicated identification of the object in 2009 by detecting a short tail emerging from the asteroid as it reached closest point to the Sun in its 524-day orbit. One study suggested that the Sun’s heat could create this comet activity by evaporating the sodium inside the object.

Phaeton’s obscurity may be Evidence for the existence of an intermediate stage between comets and asteroids. The discovery of non-volatile objects in comet orbits and volatile objects in typical asteroid orbits may indicate that there is, in fact, no clear-cut dividing line between these two celestial bodies.

Did you like the content? So, stay up to date with more curiosities about the universe like this on TecMundo and take the opportunity to discover what the size of a star or comet means.