VLT observations of interstellar comet 3I/ATLAS II
32 comments
·August 28, 2025galacticaactual
So how is it that nickel is present on this thing with zero corresponding iron?
reenorap
An article said this is the 3rd interstellar object detected. Are we detecting more interstellar visitors because they are getting more common, or have our techniques improved over the last few years?
synapsomorphy
Entirely the second. When Vera Rubin starts reporting its regular scans this will be made very clear because we'll probably find 10+ interstellar objects per year at minimum.
hnuser123456
These things are only a mile or two wide and at the distance of Jupiter. They require extremely sensitive and high-resolution telescopes to detect. There are probably many more of them that are smaller and further.
gus_massa
We launched a new telescope, in 2017 IIRC, that can detect them.
aardvark179
Our techniques have improved.
briffid
So is it a spaceship or not?
rdtsc
Why would do think it would be a spaceship?
lucky_cloud
I doubt they're serious but some wackos thought Oumuamua was an alien probe due to its unusual shape, and since this new interstellar object is arriving shortly after Oumuamua has left it must be the mothership.
I feel like it's more of a meme than a serious thing for most people.
chatmasta
It wasn’t a wacko theory at first. The wackos are the people who still believed it even after evidence emerged to the contrary.
andyjohnson0
The Ramans do everything in threes.
holoduke
I am getting bombarded with yt videos about this object being half the size of the sun passing our system with the planets aligned in a 0.01% chance perfect geometry etc etc. millions of views. It's incredible what people believe these days. Not a grain of skepticism.
codezero
[dead]
JPLeRouzic
This is a report about the volatile composition of interstellar objects (ISOs) passing through the Solar System.
tiahura
So telescopes can see nickel being spread at .125g/mile from 200M miles away?
dekhn
Yes, in this case the telescope (array) is composed of many elements. The scopes themselves are very sensitive (so they can detect minute amounts of photons) and the combined array gives a much higher resolution (ability to see things that are very small very far away).
astronomy technology has been improving rapidly and the VLT is one of the best implementations for this kind of problem right now.
gus_massa
An easy home experiment is to get a gas flame, like in the stovetop that is blue and sprink a little of table salt. The important part is the sodium that gives the flame a very strong yellow color.
Salts without sodium give other colors. IIRC cooper gives a green color. This is used by firecrackers makers to get nice colors, and also in the chemistry lab to detect the composition of some salts.
After studding this king of stuff for a few centuries, we have a very good idea of how each element changes the color of the flame, or absorbs some colors of the light that pass trough the mist.
JPLeRouzic
I have a 135-year-old book by Camille Flammarion that explains how astronomers were able to analyze the content of stars with spectroscopy.
dylan604
To further the reading...
DoctorOetker
for example, the element Helium (which had been presumed to exist as a missing gap in the Aufbau model, but at the time not yet discovered) was first discovered not on Earth... but in the Sun! Spectroscopy confirmed the predicted spectrum. Once The element was confirmed to exist on the sun, they started looking for it on Earth and eventually found it on Earth as well.
StableAlkyne
In the same sense that a weather radar can "see" mist dozens of miles away, yes
There is so much more information available in the electromagnetic spectrum than just the narrow range a human eye can see
exe34
my favourite today was this one: https://www.sciencedirect.com/science/article/abs/pii/S00224...
measuring pressure with line broadening!?!
We really need to be able to launch a sample return mission to interstellar objects. There’s much unique chemistry to be uncovered.