What is the difference between asteroids and comets?

For centuries, people have looked up at the night sky and wondered about what they see and beyond. Over time, with the development of the study of space and astronomy, scientists slowly began to answer these questions, naming different objects in space and predicting certain astronomical events. For those unfamiliar with the study of astronomy, these names can be confusing and difficult to remember. The best example of this is the two most commonly confused objects in space, comets and asteroids. This article examines the differences between comets and asteroids.

Why are comets made?
Comets are astronomical objects that follow a path around the Sun. These materials are made up of ice, ammonia, carbon dioxide, carbon monoxide, methane, rock, dust, and other organic compounds. Because of this structure, comets are often referred to as “dirty snowballs”.


Asteroids and comets have some things in common. They are both celestial bodies that orbit our sun, both of which have unusual orbits, sometimes close to Earth or other planets. They are both made up of materials from the formation of our solar system 4.5 billion years ago. But there are some notable differences between these two objects. The biggest difference between comets and asteroids is in their structure

While asteroids contain metals and rocks, comets are made of ice, dust, rocks, and organic compounds. As comets get closer to the Sun, some of their ice melts and evaporates, causing them to lose objects in each orbit. Asteroids are usually solid even near the Sun.

Types of comets
Comets are generally believed to fall into one of two categories: short-term and long-term.

Short-lived comets, also known as periodic comets, usually take less than 200 years to complete a complete orbit. These comets usually follow the path of other planets and solar systems, traveling as far as Jupiter and Neptune. As short-lived comets move closer to these larger planets, they are subjected to additional gravity.

Long-lived comets complete a complete orbit somewhere between 200 and 1,000 years. These solar systems not only take longer to create a complete orbit, but also take an elliptical orbit rather than a circular one. Gravitational pull from large planets attracts long-term comets outside the Solar System.

What are asteroids made of?
An asteroid is a random object orbiting the Sun. These solar system systems are often considered small planets, especially located in the interior of the Solar System. Asteroids are mainly composed of minerals and rocks. Scientists believe that asteroids contain the remains of objects that do not grow large enough to be considered a planet.

The structure of an asteroid …..
Most asteroids appear to be very similar because they have small craters on the solid surface.

As asteroids orbit the Solar System, they orbit at the same time.
. Asteroids range in size from Vesta to the largest at 329 miles (530 km) in diameter – up to 33 feet (10 m) less than the total mass of all asteroids.

Most asteroids are irregular in shape, but some are almost spherical, often with pits or craters. As they orbit the Sun in elliptical orbits, asteroids also rotate, sometimes very unstable, and slip as they go. More than 150 asteroids are known to have a small crescent moon (some have two moons). There are also binary asteroids, in which two rocks of approximately equal size orbit each other, as well as triple asteroid systems.

Types of asteroids …..
Asteroids are classified by their orbit and spectral reflection.

Based on the orbital classification, an asteroid can be a group or part of a family of asteroids. Asteroid groups are made up of a large number of asteroids that rotate together with a relatively loose fit. On the other hand, asteroid families are found very close together, and it is thought that a large asteroid originated in the past.

Currently, most asteroids reside in the asteroid belt, an area between the orbits of Mars and Jupiter that can hold millions of space rocks of different sizes. Most comets, on the other hand, are located in the farthest parts of our solar system: either 1. In the Kuiper Belt, an area just below the dwarf planet Pluto is home to millions of snow-covered comets (such as Pluto and Eris);

Some scientists believe that the asteroids formed so close to the Sun that they were too hot for any ice to form, while the comets formed so far away from the Sun that they were able to retain ice. However, other scientists now speculate that the comets in the Kuiper Belt and Oort clouds may have actually formed in the inner solar system, but may have later evolved from the gravitational effects of the giant planets Jupiter and Saturn.

The gravitational process occasionally causes asteroids and comets to deviate from their normal “(rotation term – closer to the planetary system, such as the Sun and Earth).

As comets approach the sun, some of their ice melts. This leads to another notable difference between asteroids and comets: comets have “tails”, while asteroids generally do not. As the ice in comets begins to melt and other objects evaporate from the heat of the sun, it becomes a glowing halo that extends out of the comet as it travels through space. Compounds such as ice, methane, and ammonia develop into an indistinct cloud-like shell called a coma. The forces exerted on the coma by the radiant pressure of the sun and the solar wind cause the formation of a large, elongated tail. The tails are always away from the sun.

Asteroids usually do not have tails, even near the Sun. Recently, however, astronomers have spotted some tailed asteroids, such as P / 2010A2. When the asteroid is hit or crushed by other asteroids, dust or gas is emitted from their surface, creating a tail effect. The so-called “active asteroids” are a newly accepted phenomenon, with only 13 known asteroids known so far found in the main asteroid belt, so they are very rare.

Another difference between asteroids and comets is in their orbital patterns. Asteroids have small circular orbits. Comets have very wide and elongated orbits, often exceeding 50,000 AU from the Sun. (1 AU, or unit of astronomy, equals the distance from the Earth to the Sun.) Planets and vice versa. Others, called short-lived comets, come from the Kuiper Belt and travel in small orbits around the Sun.

There is a big difference in the number of asteroids and comets … Although we do not know exactly how many asteroids or comets there are in our solar system, there is a caveat as many of them have not yet been seen. Astronomers have discovered millions of asteroids – some as small as dust particles and others measuring hundreds of kilometers. But so far, astronomers have discovered only about 4,000 comets. However, some estimates suggest that the Oort cloud could contain hundreds of billions of comets.

Scientists are studying with great interest the fact that asteroids and comets formed in the early days of our solar system. By examining them closely with satellites and landers – like the current Rosetta mission of comet 67P with Philae Lander – scientists hope to learn more about what our solar system looked like in its early days.

We also know that comets and asteroids exist in solar systems other than our own. In 2012, scientists using the Spitzer Space Telescope witnessed a crash between two large asteroids orbiting another star 1,200 light-years away. In 2011, astronomers found evidence of comets flying on a planet orbiting the star Eta Korvi, 59 light-years away from us.

Scientists are studying the possibility of comets and asteroids hitting Earth and other planets and determining what effect their collapse will have on the planet’s atmosphere. In November 2014, the comet Siding Spring came very close to Mars: a recent study suggests that 200 small asteroids or comets fall on Mars each year.

How likely is it that a large asteroid or comet will hit our planet? — We know that asteroids and comets have affected the Earth many times before orbiting them into the inner solar system. There is strong scientific evidence that cosmic collisions played a major role in the mass extinction recorded in the Earth’s fossil record. These objects, known as Near Earth Objects or NEOs, are still haunting the Earth. But NASA, ESA and other space agencies already have surveillance systems that have detected thousands of major belt asteroids and comets. . (You can find more about the topic on NASA’s Near Earth Object Program website.)

In addition, the possibility of one day mining asteroids and comets is becoming a source of interest for industrialists and commercial space ventures such as planetary resources.

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