All articles tagged with #comet
Scientists using the VLT measured carbon and nitrogen isotopic ratios in cyanide around interstellar comet 3I/ATLAS and conclude it formed in the outer regions of an old, low-metallicity star system—likely much older than the Sun—making it one of the Galaxy’s oldest known objects; future observations with the ELT will study more interstellar visitors.
In July 1994, 21 fragments of Comet Shoemaker-Levy 9 slammed into Jupiter over six days, marking the first direct observation of a collision between solar-system bodies. Triggered by Brian Marsden’s 1993 orbital prediction, a coordinated global observing effort captured unprecedented data (Hubble, Galileo, Ulysses, Voyager 2) and revealed an enormous energy release (about 40 million megatons total; fragment G ~6 million megatons) that left a 12,000-km scar. The event reshaped space policy, leading to NASA’s Spaceguard Survey in 1998 to catalog near-Earth asteroids and informing modern planetary-defense efforts such as the 2022 DART mission; it also cemented Eugene Shoemaker’s legacy in lunar exploration.
In July 2025, the ATLAS sky survey in Chile detected a faint, fast-moving object with a hyperbolic (unbound) orbit, later identified as 3I/ATLAS, the third confirmed interstellar object. Traveling about 130,000 mph, it was not a threat to Earth, with a close approach well outside the Moon’s orbit. Hubble and other facilities observed a dust plume and activity consistent with a comet, constraining the nucleus size and confirming a cometary nature. The discovery shows interstellar visitors are real and detectable with modern surveys, enabling comparative studies of material from other star systems.
Astronomers analyzing the interstellar comet suggest it formed long before the Sun, likely in another star system before being ejected into interstellar space, implying its material is much older than the Solar System and offering clues about planetary formation elsewhere.
3I/ATLAS is the third confirmed interstellar visitor to our solar system, on a hyperbolic trajectory that brought it to about 1.4 AU from the Sun in Oct 2025 and a close Earth approach in Dec 2025; Webb’s near-infrared spectra reveal a carbon dioxide–rich coma—with CO2 outweighing water by about eight to one—along with other volatiles, suggesting a nucleus intrinsically rich in CO2 and an origin well before the Sun. Isotopic and motion analyses hint at a formation roughly 10–12 billion years ago, making it possibly older than the Sun; SETI searches found no technosignatures, and the object is now outbound and fading. The event foreshadows more interstellar visitors detectable by future surveys like the Vera C. Rubin Observatory.
Astronomer Alan Hale, co-discoverer of Hale-Bopp, has died (June 6, 2026). His work helped make one of the most observed comets of the 20th century a global spectacle, visible to the naked eye for about 18 months after its 1997 perihelion; tributes from friend Leonard David and Hale’s wife Vickie reflect a life spent looking up at the skies.
In 1908 a space object exploded over Siberia in an airburst, releasing roughly 10–15 megatons of energy and flattening about 80 million trees across 830 square miles, with no crater and a ring of standing trees at the center. Scientists still debate whether it was a stony asteroid or a comet; the asteroid answer fits the ground damage while the comet explanation could account for the eerie skyglow seen across Europe. No fragment has ever been found, and the event helped spur modern planetary defense efforts, including NASA’s DART mission.
Astronomers say comet C/2025 R3 PANSTARRS — a long-period visitor likely from the Oort Cloud — has been visible in the northern hemisphere for weeks, offering a rare glimpse at material from the solar system's birth. With such comets taking extremely elongated orbits, this one may not return for around 170,000 years, making its current pass a unique opportunity to study early solar-system building blocks and clues about how planets formed, as gravitational interactions could eventually eject it from the system.
Space.com reports that Comet C/2025 R3 PanSTARRS displayed its ion tail as it passed about 45 million miles (72 million km) from Earth, with a dust tail lagging behind. The comet heated as it neared the Sun (perihelion on April 19) and then reached its closest approach to Earth around April 26, with SOHO imagery capturing the ion tail brightening and pointing away from the Sun.
A brightening Comet C/2025 R3 (PanSTARRS) will skim about 45 million miles past Earth, its closest approach on April 26, after surviving perihelion on April 19. The comet is visible in space-based imagery and can be tracked in near real time via the SOHO LASCO instrument and NOAA data feeds; it poses no threat and will fade as it moves away. Under dark southern skies it may be glimpsed with naked-eye, while binoculars reveal more detail as it traverses the solar-ward field.
Astronomers using the ALMA Observatory found that interstellar comet 3I/ATLAS contains unusually high deuterium in its water, implying it formed in a very cold, loner star-forming region long before the Sun. The object could be the oldest known interstellar visitor (up to about 11 billion years old); its nucleus is estimated to range from a quarter-mile to 3.5 miles (440 meters to 5.6 kilometers) across, and it is speeding away from the Sun at roughly 137,000 mph. The findings, published in Nature Astronomy, add context to other interstellar visitors like Oumuamua and 2I/Borisov.
ALMA measurements of deuterated water in interstellar comet 3I/ATLAS show it formed in a far colder, chemically distinct region of the Milky Way than the solar system, with deuterated-water content about 30 times higher than solar-system comets and roughly 40 times Earth's oceans.
Connecticut observers may catch a glimpse of the rare PanSTARRS comet (C/2025 R3) before sunrise this month, best with binoculars as it sits low in the eastern sky; visibility depends on clear skies and timing, with perihelion approaching and the next two mornings offering the best chances.
New measurements of interstellar comet 3I/ATLAS show its coma chemistry changing after a close pass to the Sun, with the CO2-to-water ratio shifting between observations in late 2025 and early 2026 (including Subaru data from Jan 7, 2026 and JUICE observations in Nov 2025). The results imply the comet’s internal chemistry differs from its external makeup, offering insights into planetesimal and planet formation in other star systems; the work by Yoshiharu Shinnaka and collaborators will be published in the Astronomical Journal on April 22, 2026.
Comet C/2025 R3 PanSTARRS should reach naked-eye visibility (magnitude ~4.7) in the eastern predawn sky on April 17, about 90 minutes before sunrise, low on the horizon and a few degrees above Algenib in Pegasus. Locate the Great Square and spot PanSTARRS about five degrees above the star; binoculars (10x50) can reveal its glowing nucleus. The comet will brighten toward its perihelion around April 19, then move southward and fade from Northern Hemisphere skies for the foreseeable future.