Astronomy General Space Discussion

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Snake_Baker

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NASA’s Mars orbiter spotted the ‘Star Trek’ logo on Mars and fans are freaking out

Mike Wehner June 14th, 2019

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NASA’s Mars Reconnaissance Orbiter is an incredibly useful tool that allows scientists to image areas of the planet’s surface with ultra-sharp detail. It has revealed many things about Mars and offered insights into how the planet’s weather has affected its geography over millions and sometimes billions of years.Apparently, it’s also really good at building hype with sci-fi fans. One of the orbiter’s recent images of the Red Planet is getting far more attention than most, and it’s causing quite a stir on social media. In the image, the long-still remains of an ancient dune catch the eye immediately, and for good reason: it’s in the shape of the Star Trek logo.

Mars is a dusty, windy place, and as such it has many areas that are covered in dunes. This particularly pop-culture-friendly dune is actually almost entirely gone, having been blown away by winds long ago, but its outline remains thanks to some kind of ancient eruption that caused lava to flow across it. The University of Arizona explains:

Long ago, there were large crescent-shaped (barchan) dunes that moved across this area, and at some point, there was an eruption. The lava flowed out over the plain and around the dunes, but not over them. The lava solidified, but these dunes still stuck up like islands. However, they were still just dunes, and the wind continued to blow. Eventually, the sand piles that were the dunes migrated away, leaving these “footprints” in the lava plain. These are also called “dune casts” and record the presence of dunes that were surrounded by lava.
The image, which was captured by the HiRISE camera built into the Mars Reconnaissance Orbiter, quickly spread online and, as you might expect, has become a favorite of science fiction fans. As you can see in the original image, there are actually several such fossilized dunes left in the area, all of them holding roughly the same pointy shape. In the never-ending debate between fans of Star Wars and Star Trek, it would appear that Mars has chosen a side.

https://bgr.com/2019/06/14/mars-star-trek-dune-nasa-mro/
 

Ron The Bear

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NASA’s Mars orbiter spotted the ‘Star Trek’ logo on Mars and fans are freaking out
A little sad, the way such things (Mimas = 'Death Star', travel to Mars, traces of life, aliens etc) need to be used to grab attention for the space program when most of the public couldn't otherwise give a flying fu**.
 

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I'd like to know the speed progression of the Apollo rockets during launch. Like, how fast were they going at, say 50 metres off the pad, 100m, 200m etc. I'm struggling to find it on the web.
 
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Norm Smith Medallist
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I can't be bothered looking for a more specific thread, so: Buzz Aldrin says at 44m10s into this doco about Neil Armstrong that he (Buzz) made a couple of mistakes "... fortunately, they were not that crucial". Does anyone know what they were? Was it the radar thing (or whatever) that caused the computer to reboot?

 

Wind Guard

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NASA’s Mars orbiter spotted the ‘Star Trek’ logo on Mars and fans are freaking out

Mike Wehner June 14th, 2019

View attachment 692511

NASA’s Mars Reconnaissance Orbiter is an incredibly useful tool that allows scientists to image areas of the planet’s surface with ultra-sharp detail. It has revealed many things about Mars and offered insights into how the planet’s weather has affected its geography over millions and sometimes billions of years.Apparently, it’s also really good at building hype with sci-fi fans. One of the orbiter’s recent images of the Red Planet is getting far more attention than most, and it’s causing quite a stir on social media. In the image, the long-still remains of an ancient dune catch the eye immediately, and for good reason: it’s in the shape of the Star Trek logo.

Mars is a dusty, windy place, and as such it has many areas that are covered in dunes. This particularly pop-culture-friendly dune is actually almost entirely gone, having been blown away by winds long ago, but its outline remains thanks to some kind of ancient eruption that caused lava to flow across it. The University of Arizona explains:

Long ago, there were large crescent-shaped (barchan) dunes that moved across this area, and at some point, there was an eruption. The lava flowed out over the plain and around the dunes, but not over them. The lava solidified, but these dunes still stuck up like islands. However, they were still just dunes, and the wind continued to blow. Eventually, the sand piles that were the dunes migrated away, leaving these “footprints” in the lava plain. These are also called “dune casts” and record the presence of dunes that were surrounded by lava.
The image, which was captured by the HiRISE camera built into the Mars Reconnaissance Orbiter, quickly spread online and, as you might expect, has become a favorite of science fiction fans. As you can see in the original image, there are actually several such fossilized dunes left in the area, all of them holding roughly the same pointy shape. In the never-ending debate between fans of Star Wars and Star Trek, it would appear that Mars has chosen a side.

https://bgr.com/2019/06/14/mars-star-trek-dune-nasa-mro/
An ancient dune shape on Mars that predates the pilot of Star Trek the Original Series?
 

Werewolf

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I'd like to know the speed progression of the Apollo rockets during launch. Like, how fast were they going at, say 50 metres off the pad, 100m, 200m etc. I'm struggling to find it on the web.
You could just about calculate those figures accurately soon after launch (before air resistance really kicks in) if you know the launch mass, thrust, fuel burn rate and can do a bit of calculus. There's also this chart, but extracting the numbers won't be easy:
717914

The initial velocity is due to the Earth's rotation speed at the launch latitude - that confused me for about a minute :$
 

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Wind Guard

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Great graph.
I like the red line - interesting changes in g-force during the rocket flight. Shows the three "zero-g" dips. The first one is quite sudden when the SI-C burn is completed at about 60 km altitude - from about 4g to zero-g (free fall).

When the rocket reaches about 180 km in altitude, the remaining thrust is used to increase speed to the eventual orbit free fall velocity. From the graph almost 30,000 km/hr

The reason there is zero gravity onboard satellites is not because gravity has suddenly disappeared due to the distance from the earth, but due to the fact that the satellite is in free-fall circular orbit. More a case of weightlessness.

The weight of the Earth is equal to zero due to it being in free fall motion around the Sun. It's mass doesnt change (ignoring relativistic effects which is a topic for another day my friends.)

The Earth's rotational speed depends on where you are located on the surface of the earth - latitude. So at the poles of the Earth, the rotational speed is zero and it's maximum at the equator. Not cure where this rocket launched - Florida?
 
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Snake_Baker

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Our Galaxy's Supermassive Black Hole Has Emitted a Mysteriously Bright Flare

MICHELLE STARR
12 AUG 2019

The supermassive black hole at the heart of the Milky Way, Sagittarius A*, is relatively quiet. It's not an active nucleus, spewing light and heat into the space around it; most of the time, the black hole's activity is low key, with minimal fluctuations in its brightness.

Most of the time. Recently, astronomers caught it going absolutely bananas, suddenly growing 75 times brighter before subsiding back to normal levels. That's the brightest we've ever seen Sgr A* in near-infrared wavelengths.

"I was pretty surprised at first and then very excited," astronomer Tuan Do of the University of California Los Angeles told ScienceAlert.

"The black hole was so bright I at first mistook it for the star S0-2, because I had never seen Sgr A* that bright. Over the next few frames, though, it was clear the source was variable and had to be the black hole. I knew almost right away there was probably something interesting going on with the black hole."

But what? That's what astronomers are on a mission to find out. Their findings so far are currently in press with The Astrophysical Journal Letters.

Do and his team took observations of the galactic centre using the WM Keck Observatory in Hawaii over four nights earlier this year. The strange brightening was observed on May 13, and the team managed to capture it in a timelapse, two hours condensed down to a few seconds.

 

Werewolf

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Ron The Bear

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Twenty more moons have been discovered orbiting Saturn - now up to 82 moons and there could be even more!!!

Amazing that they were discovered with an earthbound telescope, given they're all relatively tiny captured asteroids.

They must run out of Greek and Roman mythological names at some point.
 

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S5-HVS1 has left the building


S5-HVS1: Hypervelocity Star Ejected by Milky Way’s Supermassive Black Hole

Nov 13, 2019

A main-sequence hypervelocity star traveling at huge speeds after being ejected by Sagittarius A*, the supermassive black hole at the center of our Milky Way Galaxy, was spotted by an international team of astronomers.

An artist’s impression of S5-HVS1’s ejection by Sagittarius A*, the supermassive black hole at the center of the Milky Way Galaxy. Sagittarius A* and the captured binary partner to S5-HVS1 are seen far away in the left corner of the picture, while S5-HVS1 is in the foreground, speeding away from them. Image credit: James Josephides, Swinburne Astronomy Productions.

An artist’s impression of S5-HVS1’s ejection by Sagittarius A*, the supermassive black hole at the center of the Milky Way Galaxy. Sagittarius A* and the captured binary partner to S5-HVS1 are seen far away in the left corner of the picture, while S5-HVS1 is in the foreground, speeding away from them. Image credit: James Josephides, Swinburne Astronomy Productions.

Hypervelocity stars are fast-moving stars that move more than twice as fast as most other stars — more than 1 million mph (500 km/s).

Astronomers first discovered these stars in 2005. Nearly 30 HVSs have been discovered so far.

Hurtling at the blistering speed of 2.3 million mph (1,017 km/s), the newfound hypervelocity star is moving so fast that it will leave the Milky Way and head into intergalactic space.

Dubbed S5-HVS1, this star is currently located in the constellation of Grus at a distance of about 29,000 light-years.

“S5-HVS1’s velocity is so high that it will inevitably leave the Galaxy and never return,” said Dr. Douglas Boubert, an astronomer at the University of Oxford.

When integrated backwards in time, the orbit of the star points unambiguously to the Galactic center, implying that S5-HVS1 was kicked away from Sagittarius A* with a velocity of 4 million mph (1,800 km/s) and traveled for 4.8 million years to its current location.

“This is super exciting, as we have long suspected that black holes can eject stars with very high velocities,” said Dr. Sergey Koposov, a researcher at Carnegie Mellon University.

“However, we never had an unambiguous association of such a fast star with the Galactic center.”


The location of S5-HVS1 on the sky and the direction of its motion. Image credit: Sergey Koposov.
The location of S5-HVS1 on the sky and the direction of its motion. Image credit: Sergey Koposov.

Superfast stars can be ejected by black holes via the Hills mechanism, proposed by astronomer Jack Hills thirty years ago.

Originally, S5-HSV1 lived with a companion in a binary system, but they strayed too close to Sagittarius A*.

In the gravitational tussle, the companion star was captured by the supermassive black hole, while S5-HVS1 was thrown out at extremely high speed.

“This is the first clear demonstration of the Hills mechanism in action. Seeing this star is really amazing as we know it must have formed in the galactic center, a place very different to our local environment. It is a visitor from a strange land,” said Dr. Ting Li, from Carnegie Observatories and Princeton University.

The discovery was made as part of the Southern Stellar Stream Spectroscopic Survey (S5).

The astronomers used data from the 3.9-m Anglo-Australian Telescope and ESA’s Gaia satellite to reveal the full speed of the star and its journey from the Milky Way’s center.

“I am so excited this fast-moving star was discovered by S5,” said Dr. Kyler Kuehn, of Lowell Observatory.

“While the main science goal of S5 is to probe the stellar streams, we dedicated spare resources of the instrument to searching for interesting targets in the Milky Way, and voila, we found something amazing for ‘free.’ With our future observations, hopefully we will find even more.”

 

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