The Hubble Space Telescope and an explorer of Jupiter's icy moons have captured fresh images of an interstellar comet as the object makes its closest approach to Earth near the end of this month.
Comet 3I/ATLAS intrigued astronomers because it originated outside our solar system but was discovered traveling through our celestial neighborhood in July.
Given that it is only the third interstellar object ever observed streaking through our solar system, astronomers have sent multiple missions to focus on the comet. The observations played a crucial role in determining the object's trajectory and even provided clues to its composition, thanks to gases that sublimated from the comet during its flight. closest solar transit in October.
Hubble was one of the first to observe 3I/ATLAS in July, shortly after its discovery. The most detailed view of the teardrop-shaped comet yet at that time.
Astronomers spotted 3I/ATLAS again with Hubble on November 30 when it was 178 million miles (286 million kilometers) from Earth, and the telescope's Wide Field Camera 3 instrument captured an even clearer image.
Meanwhile, an image taken by the European Space Agency's Icy Moon Explorer mission, or Juice, to study Jupiter and its icy moons shows intriguing activity around the comet.
Detection of two tails
The Juice mission will explore the potential habitability of Jupiter's three largest moons: Ganymede, Calliston and Europa. Beneath the icy crust of the moons there are likely oceans that could support life.
But first Juice needs to reach Jupiter. The mission launched in April 2023 and is expected to arrive at its destination in July 2031.
And in early November, Juice was in a prime position to observe 3I/ATLAS at a distance of about 41 million miles (66 million kilometers) from the comet.
To see the comet, the spacecraft used five of its science instruments as well as the onboard navigation camera, or NavCam.
Much of Juice's data won't arrive on Earth until February because the spacecraft uses its main antenna as a heat shield to protect it from the Sun during its long journey to Jupiter. A smaller antenna transmits data back at a lower speed.
The Juice team didn't want to wait that long, so they uploaded a quarter of the NavCam image. The image shows the comet's thermal activity as it passes close to the Sun.
The newly released image shows a coma, or glowing halo of gas, surrounding the comet, as well as two tails: a plasma tail made of electrically charged gas, and a faint dust tail made of released particulate matter.
On November 2, the Jupiter Icy Moons Explorer satellite's NavCam observed two tails flying off the comet. – ESA/Juice/NavCam
Comets born in our solar system usually have both of these tails, as well as a hazy coma surrounding a solid core of rock, gas, dust and ice left over from the formation of the Sun, planets or other celestial bodies. When comets approach stars like our Sun, they heat up, forming tails of sublimating material that sweep behind them.
Comet 3I/ATLAS will pass within 167 million miles (270 million kilometers) of Earth on December 19, but it will be on the other side of the Sun and poses no threat to our planet. For reference, the Earth is about 93 million miles (150 million kilometers) from the Sun. According to NASA, the comet is expected to remain visible to telescopes and space missions for several more months before leaving our solar system.
Juice's remaining data on the comet's flyby, expected between February 18 and 20, should include images from the spacecraft's high-resolution optical camera, as well as composition and particle data that could provide more clues about where the interstellar object came from.
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