Changes in Ceres’s white spots
The uncertainty of science: Ground-based observations of Ceres now suggest that the white spots imaged by Dawn undergo subtle unexpected variations
As Ceres rotates every 9 hours, HARPS is so sensitive that it can detect the very slight Doppler shift in spectrum frequency as the bright spots rotate toward and away Earth, but during observations for 2 nights in July and August 2015, more changes not related to Ceres’ spin were detected. “The result was a surprise,” said co-author Antonino Lanza, also from the INAF–Catania Astrophysical Observatory. “We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.”
And it appears that these changes are consistent with some kind of volatile (ice) being exposed to sunlight and venting vapor into space, causing an increase in reflectivity. It seems that when Occator experiences solar heating, plumes are produced and then evaporate, creating a complex spectroscopic signal that evolves during that hemisphere’s daytime. This finding appears to be consistent with earlier observations made by Dawn showing a mysterious haze over Occator.
The problem with this theory is that it assumes the white spots are comprised of water ice. However, data from Dawn has instead suggested that the white spots are not water but salt deposits.
It could be that the white spots are salt left behind when water vented from inside Ceres evaporates away, but so far the data from Dawn has not found any evidence of water at the spots. If it was venting there, Dawn should have seen it.
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 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
The uncertainty of science: Ground-based observations of Ceres now suggest that the white spots imaged by Dawn undergo subtle unexpected variations
As Ceres rotates every 9 hours, HARPS is so sensitive that it can detect the very slight Doppler shift in spectrum frequency as the bright spots rotate toward and away Earth, but during observations for 2 nights in July and August 2015, more changes not related to Ceres’ spin were detected. “The result was a surprise,” said co-author Antonino Lanza, also from the INAF–Catania Astrophysical Observatory. “We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.”
And it appears that these changes are consistent with some kind of volatile (ice) being exposed to sunlight and venting vapor into space, causing an increase in reflectivity. It seems that when Occator experiences solar heating, plumes are produced and then evaporate, creating a complex spectroscopic signal that evolves during that hemisphere’s daytime. This finding appears to be consistent with earlier observations made by Dawn showing a mysterious haze over Occator.
The problem with this theory is that it assumes the white spots are comprised of water ice. However, data from Dawn has instead suggested that the white spots are not water but salt deposits.
It could be that the white spots are salt left behind when water vented from inside Ceres evaporates away, but so far the data from Dawn has not found any evidence of water at the spots. If it was venting there, Dawn should have seen it.
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 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
Readers: the rules for commenting!
No registration is required. I welcome all opinions, even those that strongly criticize my commentary.
However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.
Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.