let us take a look at the wanderers of our solar system, the comets, meteors, and asteroids.
“This most beautiful system of the sun, planets, and comets, could only proceed from the counsel and dominion of an intelligent and powerful being”
– Isaac Newton
If I tell you to recall a wonderful phenomenon that happens in the night sky, you are probably thinking of a meteor shower or a comet passing by the solar system.
That’s the thing about them. Celestial showers are like firecrackers, they are like the celebrations of our solar system.
They are often known as the “snowballs”. But unlike the snowballs we know, these tend to be made up of frozen gasses, rocks and dust.
Comets orbit around the Sun in their own well-defined orbits. When frozen they can be the size of a small town. But when this comet approaches closer to the Sun, it gets heated up and sweeps al the gas and dust forming a large glowing tail.
The tail of a comet can be larger than most of the planets. The dust and gasses are always directed in a direction that is opposite to that of the Sun.
The tail of a comet can stretch up to millions of miles away.
It is estimated that there are about a billion comets that are orbiting around the Sun and many more in the distant Oort cloud.
Do you want to know, from these billions of comets how many have been yet discovered?
Well, then you’ll be surprised to know that until today 3,535 comets have been discovered.
Where do they come from…
These icy objects, occasionally get pushed by gravity into the orbits bringing them closer to the Sun. Now, some of the comets become the so-called short-period comets, they can take less than 200 years to orbit the Sun.
Most of them originate from the Oort cloud region. These Oort cloud comets can take as long as 30 million years to complete one trip around the Sun.
A comet mainly comprises of three parts:
This is a tiny frozen part of the comet that makes up the front of the comet. It is often no larger than a few kilometers across. Comprises mainly of icy chunks, frozen gasses with bits of embedded dust.
When the comet gets near the Sun, it warms up and develops an atmosphere around it this atmosphere is called the coma of the comet. As it gets nearer to the Sun the coma becomes larger and larger. The coma of a typical comet may extend up to thousands of kilometers, as a result of high-speed solar particles or what we know as the solar wind.
Tail – the result, a long bright tail made up of gas and dust that has blown from the coma away from the sun.
Hits on Earth…
Celestial impacts on Earth may sound scary! But such events are responsible for most of the important things that have today. For example the formation of the Earth-moon system, the evolutionary history of life, the origin of life on Earth, several mass extinctions, etc.
After an impact event on a solid object, what’s left is an impact structure. On many parts of our Earth’s solid surface, the most solid evidence of prehistoric events can be seen. Some of such events that took place on Earth are:
The Late Heavy Bombardment. This occurred early in the history of the Earth-moon system.
Chicxulub. Took place 66 million years ago, and is believed to be the cause of the Cretaceous – Paleogene Extinction Event.
those with a diameter of above 5km (3mi) happen approximately once every 20 million years. The last known large asteroid that had hit Earth’s surface was 10 km (6mi) or more in diameter, this event took place during the Cretaceous – Paleogene Extinction that is near 66 million years ago.
Meteoroid, Meteor, and Meteorite…
Often people get confused between these three terms. Now, worry not!
this is a small rocky or metallic body in outer space. This is smaller than an asteroid. The size of such an object in the space can vary from that of a small grain to one meter wide. But yes, there are meteoroids that are smaller than that. These are called micrometeoroids or space dots.
About their formation
These space wanderers are actually fragments ejected from comets and asteroids and also the leftovers that get ejected into space after a collision of moon or Mars with asteroids and comets.
When these meteoroids enter the Earth’s atmosphere with speeds that can go up to 20km/s (72,000km/hr), aerodynamic heating takes place due to which we see a streak of light. This phenomenon is termed as a meteor or what we like to call it, a shooting star!
When many such meteors appear some seconds or minutes apart in the same part of the sky, it is a meteor shower.
The last stage. If the meteor survives the Earth’s atmosphere then it will make an impact on the Earth’s surface. It is now called a meteorite.
A bright comet?
It was January 2007. Remember that time? We all were just so excited to see the biggest comet streak across the sky. Comet McNaught. It was recorded as the brightest since 1965. In some places, it was visible to the naked eye in broad daylight. Its tail was 35 degrees long, if you wonder how long that is, it is the same apparent size as 70 full moons lined up in the sky.
Oh, that’s close!
Hyakutake discovered on 31st January 1996. Its orbit leads it so close to Earth that it was recorded as the closest cometary approaches of the last 200 years, 15 million kilometers (believe me, that’s very close!).
It was very bright and was seen around the world. It was called “The Great Comet Of 1996”.
We cannot end this article on comets without including one of the most well known and loved comet, “The Halley’s Comet”.
Being a periodic comet, Halley returns to Earth’s vicinity after every 75 years. This makes it possible for us to view it at least once in our lifetime. And if you are really lucky, maybe twice!
The last time that it gave a visit was in 1986 and will be returning again in 2061. Oh, I just can’t imagine how much happiness and joy it’ll get this time.
The comet was named after an English astronomer Edmond Halley who happened to examine its reports. He saw in the reports a comet that approached Earth in 1531, 1607 and in 1682.
After a lot of research, he concluded that all the three comets were not different but one single comet that kept returning over and over again. He had even predicted its next visit that would be in 1758.
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