Martian auroras as seen by UAE’s Al-Amal orbiter
Click for full image.
Using data gathered by the Al-Amal orbiter (“Hope” in English), scientists have identified three types of aurora on Mars. The image to the right, figure 1 from their paper, shows these types, crustal field aurora, patchy aurora, and sinuous aurora. From the abstract:
We categorize discrete auroral patterns into three types: those near strong vertical crustal magnetic field, patchy aurora near very weak crustal fields, and a new type we call “sinuous,” an elongated serpentine structure that stretches thousands of kilometers into the nightside from near midnight in the northern hemisphere.
All three types generally occur during the Martian night, and evolve quickly over periods of less than 45 minutes. The first type, which is generally the brightest, forms over terrain where Mars’ residual magnetic field is strongest and vertically oriented, and was most often seen over the southern cratered highlands centered between the large impact basins Argyre and Hellas. The third type, sinuous aurora, was more unusual:
These we are calling “sinuous discrete aurora,” due to their thin, elongated, and sometimes serpentine shapes. They share several key traits: (a) they appear in the northern hemisphere away from strong crustal fields, (b) they usually connect to the dayside in the far north but also sometimes separately at lower latitudes, (c) they extend for thousands of kilometers into the night side, (d) they appear on both dusk and dawn sides, and (e) their shapes change moderately and brightnesses shift by factors of up to two over timescales of ∼20 min (i.e., the time between swaths, as shown in the differences between Figures 1j and 1k [in the figure above).
The existence of aurora on Mars has been known since the 2000s. These observations however are the first that show more details beyond a fuzzy patch.
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
Click for full image.
Using data gathered by the Al-Amal orbiter (“Hope” in English), scientists have identified three types of aurora on Mars. The image to the right, figure 1 from their paper, shows these types, crustal field aurora, patchy aurora, and sinuous aurora. From the abstract:
We categorize discrete auroral patterns into three types: those near strong vertical crustal magnetic field, patchy aurora near very weak crustal fields, and a new type we call “sinuous,” an elongated serpentine structure that stretches thousands of kilometers into the nightside from near midnight in the northern hemisphere.
All three types generally occur during the Martian night, and evolve quickly over periods of less than 45 minutes. The first type, which is generally the brightest, forms over terrain where Mars’ residual magnetic field is strongest and vertically oriented, and was most often seen over the southern cratered highlands centered between the large impact basins Argyre and Hellas. The third type, sinuous aurora, was more unusual:
These we are calling “sinuous discrete aurora,” due to their thin, elongated, and sometimes serpentine shapes. They share several key traits: (a) they appear in the northern hemisphere away from strong crustal fields, (b) they usually connect to the dayside in the far north but also sometimes separately at lower latitudes, (c) they extend for thousands of kilometers into the night side, (d) they appear on both dusk and dawn sides, and (e) their shapes change moderately and brightnesses shift by factors of up to two over timescales of ∼20 min (i.e., the time between swaths, as shown in the differences between Figures 1j and 1k [in the figure above).
The existence of aurora on Mars has been known since the 2000s. These observations however are the first that show more details beyond a fuzzy patch.
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
One wonders why Mars’ southern hemisphere possesses a residual magnetic field capable of hosting auroras and the northern hemisphere does not.
Once having a global magnetic field, now not, what has made the difference?
A big iron asteroid impacting in the southern hemisphere while a global field still existed capturing some of it?