The incoming comet is like nothing scientists have seen before and is believed to have come from another star system.
That makes the visitor, known as 2I/Borisov, only the second interstellar object ever spotted in our Solar System.
Discovered in August, Borisov has travelled at least 7trillion miles to get here and will make its close approach with Earth next month.
Experts captured a closeup of the object on Sunday using a telescope at the Keck Observatory in Hawaii.
The image, taken by Yale University scientists, showed the comet surrounded by a bright white glow.
Made up of ice and other debris crumbling from Borisov’s main body, the ghostly tail stretches a staggering 100,000 miles long.
That makes it longer than 12 Earths stacked side by side behind the comet.
“It’s humbling to realise how small Earth is next to this visitor from another solar system,” said Yale scientist Dr Pieter van Dokkum.
Borisov is only the second interstellar object spotted in our cosmic neighbourhood. The first was ‘Oumuamua in 2017.
Travelling at around 110,000mph, the interloper will pass roughly 190million miles from Earth in December, according to Nasa.
That’s about twice the average distance from Earth to the Sun.
Borisov’s breakneck speed indicates it came from interstellar space, and will likely return there again sometime next year.
Unlike Oumuamua, which was only spotted as it sped past Earth, scientists saw Borisov coming weeks before its visit.
What is Oumuamua?
Here’s everything you need to know…
- Oumuamua is a cigar-shaped asteroid that sped past Earth in 2017
- Some boffins think the space rock was an alien probe sent by a distant civilisation
- It was spotted by scientists in Hawaii, and its name means ‘scout’ in Hawaiian
- Researchers involved in SETI- the Search for Extra Terrestrial Intelligence – used a powerful dish to scan Oumuamua
- They found no signs of radio signals, suggesting it wasn’t an alien spaceship after all
- Recent research suggests that the object could have been ejected by a gas giant planet
- It’s now moving away from Earth so fast that we’re unlikely to ever find out
This has allowed them to study it extensively before it shoots off into interstellar space again.
“Comet Borisov will eventually leave our Solar System,” University of California astronomer Dr Paul Kalas wrote last month.
“Until then we should all enjoy the marvellous beauty of our alien comet friend.”
Despite numerous attempts to study Borisov, scientists remain clueless as to what it is. Many speculate the distant mass is a comet.
Experts say it’ll take a few more months to plot the object’s full trajectory, which may yield clues as to what it is and where it came from.
In studying it, scientists hope to shed light on how comets and other objects form in distant star systems.
The goal is to get a better understanding of how the universe ticks outside of our Milky Way.
According to prominent astronomer Dr Seth Shostak, 76, we can’t say for sure Borisov is not an alien probe sent to study our planet.
“We can’t rule out that this is an interstellar probe,” Dr Shostak, a senior astronomer at the SETI Institute in California, told The Sun in September.
“If we get a closeup look, we may well see it has a metal exterior with portholes and little green faces looking out at us.
“However, I would bet next month’s pay cheque this is a comet.”
And, there may have been a breakthrough in the search for alien life as scientists pinpoint the exact location of a mysterious fast radio burst that could be a signal from ET.