New Hubble observations of Comet 3I/Atlas refine its size
Click for original image.
Using the Hubble Space Telescope, astronomers have refined significantly the size of the interstellar object Comet 3I/Atlas as it zips through the solar system in its journey through the galaxy.
The image to the right, cropped and reduced to post here, is a Hubble image taken on July 21, 2025. The streaks are background stars.
Hubble’s observations allow astronomers to more accurately estimate the size of the comet’s solid, icy nucleus. The upper limit on the diameter of the nucleus is 3.5 miles (5.6 kilometers), though it could be as small as 1,000 feet (320 meters) across, researchers report. Though the Hubble images put tighter constraints on the size of the nucleus compared to previous ground-based estimates, the solid heart of the comet presently cannot be directly seen, even by Hubble.
…Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 300 million miles from the Sun. This behavior is much like the signature of previously seen Sun-bound comets originating within our solar system.
In other words, though this object comes from far outside our solar system, it so far appears to closely resemble comets from our own system. If confirmed, this fact is quite significant, as it suggests the formation of solar systems throughout the galaxy are likely to be relatively similar to our own.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for original image.
Using the Hubble Space Telescope, astronomers have refined significantly the size of the interstellar object Comet 3I/Atlas as it zips through the solar system in its journey through the galaxy.
The image to the right, cropped and reduced to post here, is a Hubble image taken on July 21, 2025. The streaks are background stars.
Hubble’s observations allow astronomers to more accurately estimate the size of the comet’s solid, icy nucleus. The upper limit on the diameter of the nucleus is 3.5 miles (5.6 kilometers), though it could be as small as 1,000 feet (320 meters) across, researchers report. Though the Hubble images put tighter constraints on the size of the nucleus compared to previous ground-based estimates, the solid heart of the comet presently cannot be directly seen, even by Hubble.
…Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 300 million miles from the Sun. This behavior is much like the signature of previously seen Sun-bound comets originating within our solar system.
In other words, though this object comes from far outside our solar system, it so far appears to closely resemble comets from our own system. If confirmed, this fact is quite significant, as it suggests the formation of solar systems throughout the galaxy are likely to be relatively similar to our own.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
It seems to confirm stuff seen in a telescope this time looks much like stuff seen in a telescope every time before. Astounding!
Sure would be nice if NASA Acting Administrator would accept Jared Issacman’s suggestion of a reboost and maintenance visit to Hubble