The interstellar comet 3I/ATLAS continues approaching Earth and, thanks to this, both NASA and the European Space Agency (ESA) were able to obtain new, much sharper images. This object, discovered in July, is only the third confirmed object from outside the solar system by scientists. It travels at approximately 210,000 kilometers per hour and had its closest approach to the Sun on October 29, which considerably increased its activity.
As the date of its closest approach to Earth, scheduled for December 19, draws near, observations have become more detailed. The space agencies detected that its recent passage by the Sun left it especially bright and active, expelling large quantities of gas and dust.
NASA shared an image taken on December 3 by the Hubble telescope, where the comet’s nucleus and the coma, the cloud of gas and dust surrounding it, can be clearly seen.
The new images also reveal a striking phenomenon: the presence of two tails. The ESA explained that “we not only clearly see the bright halo of gas surrounding the comet, known as the coma, but we also see an indication of two tails.... The comet’s ‘plasma tail’, formed by electrically charged gas, extends toward the upper part of the image. We might also be seeing a fainter ‘dust tail’, composed of tiny solid particles, extending toward the lower left of the frame.”
This double structure indicates that the object is going through a period of intense activity as it continues its journey.
In addition to the tails, astronomers detected unusual behavior they described as a “heartbeat.” New observations revealed jets of gas and dust shooting out in rhythmic bursts every 16.16 hours, creating an intermittent brightness that increases and decreases 20 to 40% repetitively.
This pulse drew attention because some suggested it might not be a common comet; however, both NASA and ESA insist it is a natural object with no signs of extraterrestrial life.
Scientists explain the phenomenon simply: the comet’s nucleus rotates once every 16.16 hours and has ice zones that, when exposed to the Sun, heat up and pass directly to gas, generating jets that are released “like clockwork.” The expelled material can reach up to 985 mph and travel nearly 15,900 miles, giving rise to the luminous pulse observed from Earth.
Even so, some researchers consider the brightness too intense to be explained solely by the nucleus’s rotation. Scientist Avi Loeb pointed out that most of the light comes from the gigantic coma surrounding the comet, not from the dark nucleus.
From his perspective, if only the nucleus were generating the jets, the large cloud should smooth out those flashes. Calculations suggest the brightness should barely vary by 5%, not between 20% and 40%.
The astrophysicist highlighted other anomalies in previous observations, though NASA completely ruled out that it is something unnatural.
Scientists discovered this “heartbeat” using ground-based telescopes and recording changes in brightness over time. The exact repetition of the cycle was first reported in a study published in August 2025.
According to this data, the pulse could have remained active since the object entered the solar system, long before its discovery.
Despite doubts raised by some experts, the space agencies reiterate that 3I/ATLAS represents no threat. Its closest approach will occur on December 19, when it will pass approximately 270 million kilometers according to NASA measurements, or 170 million miles according to other estimates. In any case, it will remain a completely safe distance. This approach will allow continued study of the comet and improve monitoring of objects that could represent real risks in the future.
What will happen on December 19, the date of the interstellar comet 3I/ATLAS’s closest approach to Earth
December 19, 2025 will be the date of the interstellar comet 3I/ATLAS’s closest approach to Earth.
The importance of this day lies in the fact that it will be the best moment to attempt observation of this cosmic traveler. The comet is expected to be visible in the morning sky, moving near constellations such as Virgo and Leo.
Once it passes this point, 3I/ATLAS will continue its path toward the confines of the Solar System, leaving it permanently.
