Impact on the Moon during the January 2019 lunar eclipse
Observers watching January’s total eclipse of the Moon saw a rare event, a short-lived flash as a meteorite hit the lunar surface. Spanish astronomers now think the space rock collided with the Moon at 61,000 kilometres an hour, excavating a crater 10 to 15 metres across. ...
Total lunar eclipses take place when the Moon moves completely into the shadow of the Earth. The Moon takes on a red colour – the result of scattered sunlight refracted through the Earth’s atmosphere - but is much darker than normal. These spectacular events are regularly observed by astronomers and the wider public alike.
The most recent lunar eclipse took place on 21 January 2019, with observers in North and South America and western Europe enjoying the best view. At 0441 GMT, just after the total phase of the eclipse began, a flash was seen on the lunar surface. Widespread reports from amateur astronomers indicated the flash – attributed to a meteorite impact - was bright enough to be seen with the naked eye. ...
The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts. ...
Multiwavelength observations of a bright impact flash during the 2019 January total lunar eclipse ~ José M Madiedo et al
<<Giordano Bruno is a 22-kilometre lunar impact crater on the far side of the Moon, just beyond the northeastern limb. It lies in an area that can be viewed during a favorable libration, although the area is viewed from the side and not much detail can be seen. It lies between the craters Harkhebi to the northwest and Szilard to the southeast.
When viewed from orbit, Giordano Bruno is at the center of a symmetrical ray system of ejecta that has a higher albedo than the surrounding surface. The ray material extends for over 150 kilometres and has not been significantly darkened by space erosion. Some of the ejecta appear to extend as far as the crater Boss, over 300 kilometres to the northwest. The outer rim of the crater is especially bright compared to its surroundings. To all appearances, this is a young formation that was created in the relatively recent past, geologically speaking. Based on photos from a lunar orbiter, the crater's age has been estimated at 4 million years.
Five monks from Canterbury reported to the abbey's chronicler, Gervase, that shortly after sunset on 18 June 1178, (25 June on the proleptic Gregorian calendar) they saw "the upper horn [of the moon] split in two". Furthermore, Gervase writes:
From the midpoint of the division a flaming torch sprang up, spewing out, over a considerable distance, fire, hot coals and sparks. Meanwhile the body of the Moon which was below writhed, as it were in anxiety, and to put it in the words of those who reported it to me and saw it with their own eyes, the Moon throbbed like a wounded snake. Afterwards it resumed its proper state. This phenomenon was repeated a dozen times or more, the flame assuming various twisting shapes at random and then returning to normal. Then, after these transformations, the Moon from horn to horn, that is along its whole length, took on a blackish appearance.
In 1976, the geologist Jack B. Hartung proposed that this described the formation of the crater Giordano Bruno.
Modern theories predict that a (conjectural) asteroid or comet impact on the Moon would create a plume of ejecta rising up from the surface, which is consistent with the monks' description. The impact would be expected to perturb the Moon's motions, and laser rangefinding measurements of its libration in longitude were judged to be of the expected magnitude for such an event. In addition, the location recorded fits in well with the crater's location. Additional evidence of Giordano Bruno's youth is its spectacular ray system. The ratio of the length of these rays to the diameter of the crater is the largest for a large crater on the moon, suggesting it is the youngest such crater. Because micrometeorites constantly rain down, they kick up enough dust to quickly (in geological terms) erode a ray system.
However, these observations do not resolve the question of the crater's age. The expected odds of formation of a lunar crater of that size in the last 3000 years are on the order of 0.1%. The impact creating the 22-km-wide crater would have kicked up 10 million tons of debris, triggering a week-long, blizzard-like meteor storm on Earth – yet no accounts of such a noteworthy storm of unprecedented intensity are found in any known historical records, including the European, Chinese, Arabic, Japanese and Korean astronomical archives. This discrepancy is a major objection to the theory that Giordano Bruno was formed at that time. Also, much older craters, e.g., Tycho at 108 million years and Copernicus at an estimated 800 million years, still have prominent ray systems.
High-resolution images obtained by the Japanese satellite SELENE in 2008 were used to date the crater by counting the smaller craters within it and its ejecta deposits. This gave an age of 4+6−3 million years, much too old for the hypothesis.
This raises the question of what the monks saw. An alternative theory holds that the monks just happened to be in the right place at the right time to see an exploding meteor coming at them and aligned with the Moon. This would explain why the monks were the only people known to have witnessed the event; such an alignment would only be observable from a specific spot on the Earth's surface.>>
Re: RAS: Space Rock Hit the Moon at 61,000 kph
Posted: Wed May 01, 2019 9:16 pm
by BDanielMayfield
Or about 17 km/s, in the more usual way of reporting speeds in space.
Re: RAS: Space Rock Hit the Moon at 61,000 kph
Posted: Wed May 01, 2019 11:53 pm
by neufer
BDanielMayfield wrote: ↑Wed May 01, 2019 9:16 pm
Or about 17 km/s, in the more usual way of reporting speeds in space.
I, too, hate the silly "per hour" speed designations.
300,000 km/s = speed of light
300 km/s ~ minimal solar wind speed
30 km/s ~ speed of the Earth around the sun
300 m/s ~ speed of sound in air
30 m/s ~ speed of a fast car
Everyone should memorize these speeds per second
and not have to translate them to speeds "per hour."
300,000 km/s = speed of light
300 km/s ~ minimal solar wind speed
30 km/s ~ speed of the Earth around the sun
300 m/s ~ speed of sound in air
30 m/s ~ speed of a fast car
Everyone should memorize these speeds per second
and not have to translate them to speeds "per hour."
Nice, Art. That's a list of velocities that I should try to memorize.
Ann
Re: RAS: Space Rock Hit the Moon at 61,000 kph
Posted: Thu May 02, 2019 11:46 pm
by rstevenson
3 m/s ~ me approaching a just BBQed hamburger
Rob
Re: RAS: Space Rock Hit the Moon at 61,000 kph
Posted: Fri May 03, 2019 1:53 am
by Nitpicker
Just filling in some gaps ...
30,000 km/s ~ maximal supernova expulsion speed
3,000 km/s ~ redshift speed of Centaurus Cluster of galaxies
3 km/s ~ speed for geostationary orbit of Earth
Re: RAS: Space Rock Hit the Moon at 61,000 kph
Posted: Fri May 03, 2019 3:39 am
by bystander
Nitpicker wrote: ↑Fri May 03, 2019 1:53 am
Just filling in some gaps ...
30,000 km/s ~ maximal supernova expulsion speed
3,000 km/s ~ redshift speed of Centaurus Cluster of galaxies
3 km/s ~ speed for geostationary orbit of Earth
