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Scientists discover 3I/ATLAS, possibly the oldest comet, predating our entire solar system by more than 3 billion years.

What is Comet 3I/ATLAS?

Scientists using the ATLAS survey telescope in Chile first spotted it, and named it 3I/ATLAS. The "I" in its name stands for "interstellar," meaning it comes from outside our own solar system.

Why is 3I/ATLAS Considered an Interstellar Object?

Its Orbit => It follows a "highly elliptical orbit" around the Sun, unlike the more circular paths of planets. Its orbit is "hyperbolic", and it will exit our solar system. Objects from our own solar system orbit the Sun repeatedly.

Its Speed => It is moving at the speed of about 57-68 kilometers per second, too high for an object that originated within our Sun's gravitational pull.

Its Origin Direction => Its path traces back to the direction of the constellation Sagittarius, indicating it came from deep space.

Will 3I/ATLAS Pose a Threat to Earth?

3I/ATLAS will not pose any threat to Earth. NASA has confirmed this. Its closest approach to our planet will still be a very safe distance of about 270 million kilometers away. This is much farther than the distance between Earth and Mars.

What Is a Comet?

A comet is a small celestial body made mostly of ice (water ice, carbon dioxide ice, methane ice, etc.), mixed with dust, rock particles, and frozen gases.

When they are far from the Sun => Comets are completely frozen, dormant, and appear very dark. They are relatively small then, just a few kilometers (a few miles) wide.

When they get close to the Sun => As a comet approaches the Sun, the Sun's heat warms it up. The ice inside begins to turn directly into gas, skipping the liquid stage. This gas and dust burst out from the comet's core.

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Important Note: A comet's tail always points away from the Sun, no matter which direction the comet is moving.

What are the Different Types of Comets?

Short-Period Comets

• Orbital Period => These comets complete an orbit around the Sun in less than 200 years.
• Origin => They come from the Kuiper Belt.
• Appearance => They usually have more regular and predictable orbits.
• Example => Halley's Comet is a famous short-period comet, appearing about every 76 years.

Long-Period Comets:

• Orbital Period => These comets take more than 200 years to orbit the Sun, sometimes thousands or even millions of years.
• Origin => They come from the much more distant Oort Cloud.
• Appearance => Their orbits are usually very stretched out and often less predictable. Some may pass by the Sun only once before being flung out of the solar system forever.
• Example => Comet Hale-Bopp (visible in 1997) was a long-period comet.

Interstellar Comets:

• Origin => These comets originate from outside our own solar system, traveling from other star systems.
• Behavior =>They move so fast that our Sun's gravity cannot capture them into an orbit, so they usually pass through our solar system once and then continue their journey through interstellar space.
• Rarity => They are extremely rare to observe. As of now, scientists have only confirmed a few, such as 1I/'Oumuamua (an asteroid-like object) and 2I/Borisov (a comet-like object), and the recently discovered 3I/ATLAS.

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Source: 

THE HINDU