Starship Asterisk*

Ann wrote: ↑Fri Nov 01, 2019 5:38 amMars looks very bright in this picture. Was Mars actually close to Earth when this picture was taken? Or does Mars look so bright because it was just so much brighter than the tiny little comet?

Case wrote: ↑Fri Nov 01, 2019 8:39 am

Ann wrote: ↑Fri Nov 01, 2019 5:38 amMars looks very bright in this picture. Was Mars actually close to Earth when this picture was taken? Or does Mars look so bright because it was just so much brighter than the tiny little comet?

According to Stellarium, Mars was at mag 0.87 and 1.632 AU distance, at that time. Mars can be at mag -2, and as close as 0.37 AU. So, it isn’t particulary bright here.

Ann wrote: ↑Fri Nov 01, 2019 5:38 am Mars looks very bright in this picture. Was Mars actually close to Earth when this picture was taken? Or does Mars look so bright because it was just so much brighter than the tiny little comet?

Trailblazer wrote: ↑Fri Nov 01, 2019 2:18 pm
I was wondering why you didn't mention Orson Welles -
He was, after all, the genius behind the 1938 broadcast that created all the panic back then.

https://en.wikipedia.org/wiki/Leonhard_Euler wrote:

Click to play embedded YouTube video.

<<Leonhard Euler (15 April 1707 – 18 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician and engineer who made important and influential discoveries in many branches of mathematics, such as infinitesimal calculus and graph theory, while also making pioneering contributions to several branches such as topology and analytic number theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion of a mathematical function. He is also known for his work in mechanics, fluid dynamics, optics, astronomy and music theory. Euler was one of the most eminent mathematicians of the 18th century and is held to be one of the greatest in history. He is also widely considered to be the most prolific mathematician of all time. His collected works fill 92 volumes, more than anyone else in the field. A statement attributed to Pierre-Simon Laplace expresses Euler's influence on mathematics: "Read Euler, read Euler, he is the master of us all.">>

https://en.wikipedia.org/wiki/Bernoulli_family wrote:
<<The Bernoulli family of Basel was a patrician family, notable for having produced eight mathematically gifted academics who, among them, contributed substantially to the development of mathematics and physics during the early modern period.>>

https://en.wikipedia.org/wiki/C/2013_A1_(Siding_Spring) wrote:
<<At the time of discovery C/2013 A1 (Siding Spring) was 7.2 AU from the Sun and located in the constellation Lepus. Comet C/2013 A1 probably took millions of years to come from the Oort cloud. C/2013 A1 passed the planet Mars very closely on 19 October 2014, at a distance of 140,500 km. During the flyby, orbiters around Mars detected thousands of kilograms per hour of comet dust composed of magnesium, iron, sodium, potassium, manganese, nickel, chromium and zinc. In addition, the comet nucleus was determined to be between 400 and 700 meters, much smaller than originally assumed. The nucleus rotates once every eight hours.>>

https://en.wikipedia.org/wiki/69230_Hermes wrote:
<<69230 Hermes, provisional designation 1937 UB, is a 810m/540m binary asteroid on an eccentric orbit, classified as a potentially hazardous asteroid and near-Earth object of the Apollo group, that passed Earth at approximately twice the distance of the Moon on 30 October 1937.

Hermes is an Apollo asteroid, a subgroup of near-Earth asteroids that cross the orbit of Earth. It orbits the Sun at a distance of 0.6–2.7 AU once every 2 years and 2 months. Its orbit has an eccentricity of 0.62 and an inclination of 6° with respect to the ecliptic. Due to its eccentricity, Hermes is also a Mars- and Venus-crosser. Frequent close approaches to both Earth and Venus make it unusually challenging to forecast its orbit more than a century in advance, though there is no known impact risk within that timeframe.

The asteroid has an Earth minimum orbital intersection distance of 0.0041 AU (610,000 km) which translates into 1.6 LD. On 30 October 1937, Hermes passed 0.00494 AU (739,000 km) from Earth, and on 26 April 1942, 0.0042415 AU (634,520 km) from Earth. In retrospect it turned out that Hermes came even closer to the Earth in 1942 than in 1937, within 1.7 lunar distances; the second pass was unobserved at the height of the Second World War. For decades, Hermes was known to have made the closest known approach of an asteroid to the Earth. Not until 1989 was a closer approach (by 4581 Asclepius) observed. At closest approach, Hermes was moving 5° per hour across the sky and reached 8th magnitude.>>

https://en.wikipedia.org/wiki/4581_Asclepius wrote:
<<4581 Asclepius (ə-SKLEE-pee-əs) is a ~300 m asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group that makes close orbital passes with Earth.

Asclepius passed by Earth on 22 March 1989, at a distance of 684,000 km. "On the cosmic scale of things, that was a close call," said Dr. Henry Holt. Geophysicists estimate that collision with Asclepius would release energy comparable to the explosion of a 600 megaton atomic bomb. The asteroid was discovered 31 March 1989, nine days after its closest approach to the Earth.>>

orin stepanek wrote: ↑Fri Nov 01, 2019 10:40 am Beautiful photo; wish one could have been taken from Mars!

Chris Peterson wrote: ↑Fri Nov 01, 2019 1:32 pm

Ann wrote: ↑Fri Nov 01, 2019 5:38 am
Mars looks very bright in this picture. Was Mars actually close to Earth when this picture was taken? Or does Mars look so bright because it was just so much brighter than the tiny little comet?

You can't even "see" Mars in this image. Just its light. At the scale of this image, Mars itself is smaller than one pixel. An unresolved point source. And yes, it's extremely bright. 36 times brighter than 51 Oph, 5000 times brighter than the comet. Far more dynamic range than our computer displays can present.

• "Mars itself is smaller than one pixel"

neufer wrote: ↑Fri Nov 01, 2019 7:18 pm

Chris Peterson wrote: ↑Fri Nov 01, 2019 1:32 pm

Ann wrote: ↑Fri Nov 01, 2019 5:38 am
Mars looks very bright in this picture. Was Mars actually close to Earth when this picture was taken? Or does Mars look so bright because it was just so much brighter than the tiny little comet?

You can't even "see" Mars in this image. Just its light. At the scale of this image, Mars itself is smaller than one pixel. An unresolved point source. And yes, it's extremely bright. 36 times brighter than 51 Oph, 5000 times brighter than the comet. Far more dynamic range than our computer displays can present.

• "Mars itself is smaller than one pixel" :?:

The Comet got as close as 21 Mars diameters away.

Chris Peterson wrote: ↑Fri Nov 01, 2019 7:57 pm

neufer wrote: ↑Fri Nov 01, 2019 7:18 pm

Chris Peterson wrote: ↑Fri Nov 01, 2019 1:32 pm
You can't even "see" Mars in this image. Just its light. At the scale of this image, Mars itself is smaller than one pixel. An unresolved point source. And yes, it's extremely bright. 36 times brighter than 51 Oph, 5000 times brighter than the comet. Far more dynamic range than our computer displays can present.

• "Mars itself is smaller than one pixel"

The Comet got as close as 21 Mars diameters away.

The pixel scale of this image (the full size click through image) is 7.1 arcseconds/pixel. At the time, Mars subtended 6 arcseconds. So it just fits inside a single pixel.

alter-ego wrote: ↑Fri Nov 01, 2019 6:44 pm

orin stepanek wrote: ↑Fri Nov 01, 2019 10:40 am Beautiful photo; wish one could have been taken from Mars!

There were, just none as visually stunning as earth-based images. Emily Lakdawalla's post 2 weeks later presents three amateur images (including today's) and mars-base images from rover Curiosity, Mars Reconnaissance Orbiter, MAVEN, Mars Express, and ISRO MOM (later post). Obviously, taking images from the orbiters involved timing and pointing adjustments. Of the (then) 5 orbiters capable of imaging the comet, only 4 were successful. The timings were spread out from minutes to hours before/after closest approach. From an ground-based observer point of view, my favorites are images from the two rovers, Curiosity and Opportunity. Curiosity showed Mar's horizon through a dusty atmosphere in twilight with a faint, point-source comet. Opportunity showed a moving, fuzzy comet trailing in a different direction than the stars.

RocketRon wrote: ↑Sat Nov 02, 2019 5:11 am If Mars is one pixel, why is the comet so many pixels. ??
That doesn't quite add up..
Even my pocket camera can do better than that.
& surely this is telescopic view ?

orin stepanek wrote: ↑Sat Nov 02, 2019 1:19 pm

alter-ego wrote: ↑Fri Nov 01, 2019 6:44 pm

orin stepanek wrote: ↑Fri Nov 01, 2019 10:40 am
Beautiful photo; wish one could have been taken from Mars!

There were, just none as visually stunning as earth-based images. Emily Lakdawalla's post 2 weeks later presents three amateur images (including today's) and mars-base images from rover Curiosity, Mars Reconnaissance Orbiter, MAVEN, Mars Express, and ISRO MOM (later post). Obviously, taking images from the orbiters involved timing and pointing adjustments. Of the (then) 5 orbiters capable of imaging the comet, only 4 were successful. The timings were spread out from minutes to hours before/after closest approach. From an ground-based observer point of view, my favorites are images from the two rovers, Curiosity and Opportunity. Curiosity showed Mar's horizon through a dusty atmosphere in twilight with a faint, point-source comet. Opportunity showed a moving, fuzzy comet trailing in a different direction than the stars.

Tnx; looks like the mars based cameras were a little bit off!

https://en.wikipedia.org/wiki/C/2013_A1_(Siding_Spring)#/media/File:PIA18611-Mars-CometSidingSpringFlyby-20141009.jpg wrote:

Mars Orbiters 'Duck and Cover' (Artist's Concept)

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Mars Orbiters 'Duck and Cover' for Comet Siding Spring Flyby

<<This artist's concept shows NASA's Mars orbiters lining up behind the Red Planet for their "duck and cover" maneuver to shield them from comet dust that may result from the close flyby of comet Siding Spring (C/2013 A1) on Oct. 19, 2014. The comet's nucleus will miss Mars by about 139,500 kilometers, shedding material as it hurtles by at about 56 kilometers per second [~12.6 lunar distances per day], relative to Mars and Mars-orbiting spacecraft. NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data. The NASA orbiters at Mars are Mars Reconnaissance Orbiter, Mars Odyssey and MAVEN.>>

https://en.wikipedia.org/wiki/C/2013_A1_(Siding_Spring)#/media/File:PIA18611-Mars-CometSidingSpringFlyby-20141009.jpg wrote:

Mars Orbiters 'Duck and Cover' (Artist's Concept)

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Mars Orbiters 'Duck and Cover' for Comet Siding Spring Flyby

<<This artist's concept shows NASA's Mars orbiters lining up behind the Red Planet for their "duck and cover" maneuver to shield them from comet dust that may result from the close flyby of comet Siding Spring (C/2013 A1) on Oct. 19, 2014. The comet's nucleus will miss Mars by about 139,500 kilometers, shedding material as it hurtles by at about 56 kilometers per second [~12.6 lunar distances per day], relative to Mars and Mars-orbiting spacecraft. NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data. The NASA orbiters at Mars are Mars Reconnaissance Orbiter, Mars Odyssey and MAVEN.>>

orin stepanek wrote: ↑Sat Nov 02, 2019 5:37 pm Yup; that was really close! Maybe Mars could have had a third moon! :mrgreen: