By Ma’rufin Sudibyo
COMET ZTF (C/2022 E3) is present near our Earth from January to February.
In the last week of January and the first week of February, comet may be visible to the unaided eye.
Also read: Why do comets have tails and how big are comets?
The presence of the traveler who once stopped in our sky in ancient times revived the conversation about the threat of danger from outer space.
When the celestial body that looks like a greenish-tipped spear blinked in the night sky about 50,000 years ago, the intelligent generation of Earth’s inhabitants was still an archaic (early) Homo sapiens struggling with its stone civilization.
Starting from the Neanderthals and CroMagnons who inhabited mainland Europe. Then the Denisova man who wandered in northern Asia. Until the Wajak humans and the dwarf Flores humans who live in the plains of southeast Asia.
When watching the evening sky after the sun sets or the dawn sky before the sun rises, they see the tailed star. Inching slowly from day to day in the foreground of the stars. Bringing cosmic secrets that are difficult to decipher for its time.
Fifty millennia later, the same comet is back in our sky.
Neanderthals and their friends are long extinct. Changing modern humans who are increasing and developing day by day, including in terms of science and technology.
Today we have the tradition and the tailed star of the ancient traveler also bears a name. Namely comet ZTF (C/2022 E3). A periodic comet with a very long orbital period, up to 50,000 years. In particular, comet ZTF (C/2022 E3) will be the brightest comet in 2023.
Of course if all the physical properties match the mathematical predictions, something that rarely happens in the world of comet astronomy.
Also read: What is a comet, a comet that orbits the sun
Comet ZTF (C/2022 E3) was discovered using a wide-angle camera attached to the 122 cm Samuel Oschin Telescope in the Zwicky Transient Facility (ZTF) program. Sky surveying program based at the Palomar Observatory, California (United States). Hence it bears the name comet ZTF.
The comet was first recorded on March 2, 2022 as a very faint speck of light, 21 times fainter than Pluto. At that time it was moving at a distance of 640 million kilometers from our Sun. Or nearly as far as Jupiter’s orbit.
Observation after observation concluded that comet ZTF (C/2022 E3) was an ancient inhabitant of our solar system. The orbit is so elliptical.
Its closest point to the Sun (perihelion) is equivalent to the distance from our Earth to the sun.
But on the other hand, its farthest point to the sun (namely aphelion) stretches very far, up to 70 times farther than Pluto’s orbit.
Comet ZTF (C/2022 E3) takes 50,000 years to complete one round of its orbit. And most of its time is spent slithering at the edge of the solar system, in the freezing cold region of the Opik–Oort comet cloud.
The comet crosses its perihelion on January 12 2023. Three weeks later, as of February 1 2023 to be precise, the comet will pass at its closest point to Earth within 42 million kilometers. Or 110 times farther than the position of the Moon to Earth. So that it does not have the potential for a cosmic collision with Earth.
Also read: Comet Tail: Definition and Types
As a bonus, the physical properties of comet ZTF (C/2022 E3) are such that it is possible to see them with the naked eye without any optical aids. To be precise, in the last week of January and the first week of February 2023.
Unlike most of the other comets we are familiar with, this comet ZTF (C/2022 E3) will appear over the northern horizon. Not far from the position of the polar star (Polaris).
Therefore the northern hemisphere is the best place to witness this comet. Even so, countries in the tropics are still likely to witness it, as long as the weather is clear and we take a really dark location (not an urban area).
Seen from Indonesia
From Indonesia, comet ZTF (C/2022 E3) is a dawn comet until early February because it only appears in the sky at dawn.
At 05:00 WIB, the comet is located in the north-northeast starting from a height of 27º (January 15) and decreasing until it is only 1º (January 29).
Approaching the end of January, the comet is getting brighter. Instead, entering February comet ZTF (C/2022 E3) has turned into a twilight comet in such a way. At 19:00 WIB, the comet will be located in the north-northwest with an increasing height but at the same time it will get dimmer, day by day.
Also read: Why Comet Borisov Might Bring Life? Expert Explain
Mitigation and DART
In various civilizations, comets have been regarded as celestial bodies that bring bad news and disaster. In the perspective of modern science and technology, this view is not completely wrong even though the context is very different.
We know that the orbits of comets are generally unstable, because they are very oval and very angular compared to the planes of the orbits of the planets. The gravitational disturbances of the planets, especially Jupiter, make their orbits shift slowly but surely.
So that if a comet only passes near a planet at one time, then in the next few orbits it could be that the accumulation of its orbital shift makes the same comet go right to that planet due to the intersection of the orbits of the two celestial bodies.
This is a cosmic collision. And the effects are truly horrific.
This is the kind of cosmic collision that our Earth experienced 66 million years ago. At that time, a celestial body as big as Mount Everest hit the Earth violently in the shallow sea waters that are now the Yucatan Peninsula.
The collision created an indescribable global impact. The long-term impact caused the extinction of the dinosaur herd along with 75 percent of the abundance of other living things (especially those with body weights > 20 kilograms).
The era of the ruling reptiles of the world ended, replaced by the era of mammals which still survives today.
Also read: Astronomers Successfully Find the Biggest Comet in the Solar System, Like What?
Comets can also be one of the celestial bodies capable of such mass destruction. In the inner solar system, comet ZTF (C/2022 E3) is traveling as fast as 57 km/s.
If it is considered to be in the shape of a ball with a center line of 1 kilometer and the composition is similar to sand, it will release the energy of 300,000 megatons of TNT when it collides with our Earth.
The energy of the collision was equivalent to 15 million Nagasaki nuclear bombs which were detonated simultaneously. The impact will form a crater 20 kilometers in diameter and eject cubic kilometers of impact dust into the sky.
Creates a global impact winter effect for many years. Destroying the order in the food chain, so that some living things have the potential to perish.
What distinguishes modern humans from dinosaurs is that we do not remain silent. Efforts to mitigate potential hazards from the sky have long been developed. And last year was one of the watershed moments.
The United States space agency (NASA) in collaboration with partners from Italy (ASI) and Japan (JAXA) has tested a method of changing orbits for celestial bodies such as asteroids through the DART (Double Asteroid Redirection Test) space mission.
On September 26, 2022, they smashed their 610-kilogram DART collider into the asteroid Dimorphos (diameter 170 km), a natural satellite of the larger asteroid Dydimos (diameter 830 meters). The direction of motion of the DART is exactly opposite to Dimorphos, so it is expected that there will be a completely inelastic collision.
Also read: The Process of Forming Comet Tails
Observations show that the collision experiment was successful, even exceeding initial expectations. The orbit of the asteroid Dimorphos has been detected to change, being 35 meters closer to its parent celestial body than before.
The orbital period was shortened by 32 minutes to 11 hours and 23 minutes compared to the previous one. This shortening of the orbital period far exceeded initial expectations, accounting for only 73 seconds.
Although it is still very early days, this success lays an additional foundation for humanity’s efforts to divert the orbit of a celestial body that is potentially dangerous for our Earth.
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