The new object known as 3I/ATLAS (C/2025 N1) has set the scientific world abuzz because it bears evidence from deep interstellar space far beyond our solar neighbourhood. Travelling at more than 130,000 miles per hour, this comet has probably formed in another star system billions of years ago and was then thrown out into interstellar space. Its hyperbolic trajectory confirms it is not gravitationally bound to the Sun, meaning once it passes through, it will never return. 3I/ATLAS is used to study how planetary systems develop and share materials across the galaxy.
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What is 3I/ATLAS?
Origin & nature:
- Its discovery was on the 1st of July, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) from Chile.
- It has a hyperbolic trajectory (e > 1), which means that it is not bound to our Sun and comes from beyond the solar system-an interstellar object indeed.
- It seems to act like a comet: outgassing, forming a coma (“atmosphere” of dust/gas), and producing a tail or jet of material.
- According to the European Space Agency (ESA), the materials of such objects might be extremely old, possibly billions of years old, to provide clues about star systems outside our own.
Why is it special?
On the records stand only two other interstellar objects, confirmed to have entered the solar system: 2I/Borisov (2019) and 1I/ʻOumuamua (2017).
Distinguishing it from normal solar system comets, it has unusual composition, size, and speed, with the James Webb Space Telescope measurement revealing that its outgassing is CO₂-dominated.
When & How to Watch-
Key Dates:
- Optimal perihelion to the Sun of 3I/ATLAS: Around 29 October 2025 at around 11:47 UTC.
- Minimum distance from the Sun: about 1.36-1.4 a.u. (~130 million miles or ~210 million km)—just inside the orbit of Mars.
- Closest approach to the Earth would be way farther: the object will always be at least ~1.8 au from Earth (~270 million km), so it poses no threat.
Visibility & Streaming:
However, because of the geometry, when the comet is at perihelion, it will be hiding on the far side of the Sun from Earth, making ground-based observations around the time of closest approach exceedingly difficult.
Some observatories and internet sites are hosting or will show the streaming of the comet through robotic telescopes; an example is the feed by the Virtual Telescope Project. Once it passes perihelion, Earth will be able to observe it progressively coming outward, probably starting from the early part of December in 2025.
How to Watch from India (or Asia/Kolkata timezone):
- Convert UTC to 11:47 UTC = 17:17 IST (Indian Standard Time) on 29 October 2025.
- By then (maybe a little before/after), check for the existence of any live streams.
- For the ground observation, you’ll require a reasonably large telescope (not just binoculars) on account of expected faintness and low elongation from the Sun.
What to Expect at Peak & After-
Activity Changes:
Coming closer to the Sun, 3I/ATLAS has come alive: e.g., a large jet of gas and dust toward the Sun that has been imaged.
It is not clear what JWST composition measurements correspond to, but they show a very high CO₂/H₂O ratio (~8 ± 1), which seems to be unusually high for comets in our solar system—indicating a different origin or formation environment.
Brightness & Tail Behaviour:
To describe “bright” is relative; it may not be visible to the naked eye from Earth because of distance and position, but could be seen through moderate to large amateur telescopes in dark conditions.
The Earth will be nearly on the opposite side of the Sun at the time of perihelion, which will make the elongation (the angle from the Sun) very small, in other words, making it quite impractical to see from Earth at the exact time of the peak.
Scientific Value:
Such astronomical events or the occurrence of rare celestial bodies like such can go a long way in scratching the surface of cosmic evolution and interstellar chemistry. The analysis of gases, dust, and isotopic ratios present in 3I/ATLAS would further benefit scientists in data comparison of the composition with that of solar system comets and, hence, the varying environments of formation, revealing regions of stellar birth across the galaxy.
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Tips for Observers & Enthusiasts-
- For better chances of seeing those faint objects, it really is best to choose dark-sky locations with a very low level of light pollution.
- For tracking and imaging faint tails or jets, a good telescope is useful (considering that the elongation is probably low).
- Check the different live stream platforms in advance so that you can enter when coverage begins.
- Follow along with observatory updates (NASA, ESA, Virtual Telescope), as new data could refine visibility windows.
- Safety note: Since the comet is close to the Sun near perihelion and will be in the same area in the sky, one should never observe the Sun without proper solar filters.
- Patience: It may show being faint and might need image stacking or patience using moderate equipment.
FAQs-
A: No. As per NASA, the comet will stay comfortably beyond 1.8 au (~270 million km) from our planet.
A: Unlikely. Given the distance and Sun-side geometry, it is expected to remain faint. Telescope viewing is recommended.
A: Best after perihelion-when the object comes out from behind the Sun and elongation improves (likely December 2025 and beyond). Before then, live telescope feeds are your best bet.
A: Several factors: interstellar origin, hyperbolic high-speed trajectory, unusual composition (e.g., CO₂-rich), and considerable scientific interest.
A: Stay tuned to agency websites (NASA, ESA), sites such as the Virtual Telescope, and astronomy news outlets. They will give live feeds, updates on activity, and tips on observing.