Any Astronomy Buffs Here?

[DevilHorse]

Perhaps NASA got a waiver... from Otis Sistrunk (local rep of the University of Mars).

Will try again on Friday.
Data expected to roll in about 1:21pm EDT.

https://www.cnn.com/2021/04/29/world...rnd/index.html

Larry
DevilHorse

4th Flight in the books, and done well!
https://www.theverge.com/2021/4/30/2...ce-new-testing

16 feet high, 164 feet down range and back.

Larry
DevilHorse

[DevilHorse]

With the originally scheduled 4 flights of Ingenuity completed with great success, NASA has extended the charter for an additional 30 days.
Now that the technical feasibility has been shown, Ingenuity will enter into a period of operational demonstrations.

Here is an article, note that there is a nice 2 minute video discussing the mission later in the article:
https://www.nytimes.com/2021/04/30/s...pter-nasa.html

https://www.nasa.gov/press-release/n...stration-phase

Going places that Perseverance can't, scouting out new landing fields, looking for interesting things for Percy to look at, are all within scope.

No details on when or where.

Ingenuity looks like an Undrafted Free Agent that joined the team. No?!d

Larry
DevilHorse

[DevilHorse]

Ingenuity supposed to be taking its 5th flight tonight (Friday 5/7/2021).
https://www.space.com/mars-helicopte...flight-preview

It is a one-way trip!

Larry
DevilHorse

[DevilHorse]

Ingenuity supposed to be taking its 5th flight tonight (Friday 5/7/2021).
https://www.space.com/mars-helicopte...flight-preview

It is a one-way trip!

Larry
DevilHorse

Success!!

https://twitter.com/NASAJPL/status/1390826543723683842

Larry
DevilHorse

[PackMan97]

Anyone close to the East Coast might be able to see a rocket launch from Virginia at 8:00 on Saturday, 5/8/21.

https://www.wral.com/colorful-aftere...oast/19664348/

[DevilHorse]

The biggest Mars news that I've heard lately is that China has landed a rover on Mars that is now exploring the red planet:
https://www.theverge.com/2021/5/22/2...ars-nasa-space
This is great news for science. There is much to learn about our angry red neighbor; the more the better.

I believe that it is through cooperation and science that we will have better cooperation between countries. Governments will screw things up unfortunately.
Duke has been at the forefront of cooperation through education with mainland china. There is a strong bond between people of our countries that will (hopefully) win the day over any political skermishes that governments can cook up.

Larry
DevilHorse

[DevilHorse]

Ingenuity is up to its 6th flight!
https://mars.nasa.gov/technology/hel...-sixth-flight/

Setting new records, but.. all was not perfect.

Larry
DevilHorse

[duke79]

https://www.express.co.uk/news/scien...relativity-evg

Turns out Einstein may have been wrong - at least on this one theory of his.

[CameronBornAndBred]

https://www.express.co.uk/news/scien...relativity-evg

Turns out Einstein may have been wrong - at least on this one theory of his.

Michael Troxel, a physicist at Duke University and the key project coordinator, said: "The real legacy of DES will be the leaps forward we’ve had to make that were essential for this key result, and which will be critical for the next generation of cosmological experiments starting soon.

"With these instruments, we’ve built to stare into the dark, we are working to solve universal mysteries."

Nice

[DevilHorse]

For those of you who want to know what the big boys are doing with their telescopes, here is the latest family picture of our Milky Way core taken with the Chandra telescope in the X-ray wavelengths.

https://www.space.com/milky-way-gala...a-photos-video

Larry
DevilHorse

[WillJ]

Can anyone provide me with a layperson's explanation of the scientific value of the 18th century observations of the Transit of Venus. My understanding is that Newton/Kepler had outlined the relative but not the absolute size of the solar system and that, to do the latter, we were going to have to triangulate the distance from earth to some other object within the solar system. That I get. What I don't get is why Transits of Venus provided a unique opportunity to execute such a measurement. Was it that Mercury is uniquely visible during such a transit? Was it that the transit facilitated the coordinated timing of measurements from distant locales in a time when clocks weren't sufficiently accurate? Something else altogether? Thanks in advance for any thoughts.

On the general topic, I love Timothy Ferriss' Coming of Age in the Milky Way, but I'm wondering whether anyone could recommend a book more narrowly on the Transit of Venus expeditions in 1761 and 1769?

[DevilHorse]

Can anyone provide me with a layperson's explanation of the scientific value of the 18th century observations of the Transit of Venus. My understanding is that Newton/Kepler had outlined the relative but not the absolute size of the solar system and that, to do the latter, we were going to have to triangulate the distance from earth to some other object within the solar system. That I get. What I don't get is why Transits of Venus provided a unique opportunity to execute such a measurement. Was it that Mercury is uniquely visible during such a transit? Was it that the transit facilitated the coordinated timing of measurements from distant locales in a time when clocks weren't sufficiently accurate? Something else altogether? Thanks in advance for any thoughts.

On the general topic, I love Timothy Ferriss' Coming of Age in the Milky Way, but I'm wondering whether anyone could recommend a book more narrowly on the Transit of Venus expeditions in 1761 and 1769?

Hi WillJ,

I would like to take a crack at it.

First I'd like to offer a good explanation of the math calculation, that I found on the internet, just in case you wanted to go through it:
https://www.exploratorium.edu/venus/question4.html

Second, I'd like to suggest why the transit of a planet is important for this.
There are limited numbers of Astronomical measurements where the actual size of the distant object, or our object (Earth) can make a difference in the measurement. In one case, you can make an observation, at the same time of something in space, from earth, and see something different, then you have a possibility of making a geometric calculation. To do this, the object you are looking at has to be in a goldilocks zone which means that the distance that you are from that object, and the distance apart (on the earth or otherwise [discussed later]) that your observations are, are large enough to allow for you to observe a difference.

This is the same observation technique that your brain does with stereo vision. For example, if you put your thumb out in front of your face at arms length and close one eye or the other, the background is slightly shifted. That is what is seen with Venus when the edge of Venus (visually) touches the sun at a different point on the earth at a different time. You instinctively know what the distance to things is. This effect is known as parallax. This effect to very distant objects requires very precise calculation. For Transits, it requires movements of the planet across the sun, or observations across the earth of the same thing in the sky.

The Parallax effect is also used at 6 months apart in the earth's orbit when looking at a field of stars (in a great circle) perpendicular to where the earth is in its orbit. Looking for shifts in points of light, relative to far off backgrounds, has enabled astronomers to determine the distance to relatively close stars.

I hope that is useful.

Larry
DevilHorse

[WillJ]

Hi WillJ,

Second, I'd like to suggest why the transit of a planet is important for this.
There are limited numbers of Astronomical measurements where the actual size of the distant object, or our object (Earth) can make a difference in the measurement. In one case, you can make an observation, at the same time of something in space, from earth, and see something different, then you have a possibility of making a geometric calculation. To do this, the object you are looking at has to be in a goldilocks zone which means that the distance that you are from that object, and the distance apart (on the earth or otherwise [discussed later]) that your observations are, are large enough to allow for you to observe a difference.

Larry
DevilHorse

Very helpful, so thank you, but let me try and follow your logic.

a) Given the constraints on how far apart we can be from one another on earth, there's a limit to how far we can use point-in-time triangulation (as you note, the measurements six-months-apart offer a dramatically wider base for the triangulation).
b) Venus is never closer to earth than during a transit since by definition, a transit occurs when Venus, Earth and the sun are collinear.
c) So the transit of venus was a unique opportunity for point-in-time triangulation because because that was when venus was closest to earth, allowing for sufficiently accurate measurements given the instruments available in the 18th century.
d) In contrast, it did not have much to do with coordinating times of observations.

Is that accurate?

[DevilHorse]

Very helpful, so thank you, but let me try and follow your logic.

a) Given the constraints on how far apart we can be from one another on earth, there's a limit to how far we can use point-in-time triangulation (as you note, the measurements six-months-apart offer a dramatically wider base for the triangulation).
b) Venus is never closer to earth than during a transit since by definition, a transit occurs when Venus, Earth and the sun are collinear.
c) So the transit of venus was a unique opportunity for point-in-time triangulation because because that was when venus was closest to earth, allowing for sufficiently accurate measurements given the instruments available in the 18th century.
d) In contrast, it did not have much to do with coordinating times of observations.

Is that accurate?

I'll try to fit my answers to your follow ons..

a') the six months apart example for parallax was for nearby stars in our galaxy (only) because they don't tend to move over 6 months. [it doesn't work for anything else astronomical like galaxies or far off stars within our galaxy]. For Venus, and Mercury, they move very fast relative to earth observations, so taking the measurements on Earth are time sensitive. But taking them at the same (approximate time, at different vertical (latitudes) gives us the geometry for our solar system that we would need.

b') the transit of a planet by the sun HAS TO be approximately when the planet is at its nearest point to us in its orbit, but not necessarily when the Earth is at its nearest point in its orbit; it is at anytime in the Earth's orbit.. right. At any time in the Earth's orbit, Venus could eclipse/transit the sun, and that makes it approximately 0 degrees with our line of sight with the sun. It is the difference between the approximately and the absolute that makes this work. Both orbits are ellipses (not circlular orbits), so the distance will vary of course. In the case of Mercury, the "ellipse" precesses in space; the famous "Precession of the Perihelion of Mercury" [You know what precession is.. it is what happens to a top when it loses steam and wobbles before it falls] that was observed since Newton's time, but only explained by Einstein's General Relativity (see https://aether.lbl.gov/www/classes/p...ionMercury.htm)... but I digress.

c') yes, I think you have it. Remember, since Galileo's time, the points of light in the sky became disks that had areas. People could look at tops and bottoms. Once they could resolve these things, then geometries and measurements could be made to Copernicus's decentralized solar system. Exciting stuff! Back then, they were really excited about different ways to measure the diameter of the earth (Kyrie missed that one in the history books). So it was natural to look out to the stars (the planets being the closest of those celestial bright things).

d') As mentioned in a', yes times did make a difference for planets that move fast. Perhaps not by the day, but by the hour if you wanted significant digits and you were not along the same meridian. It takes Venus 3 to 7 hours to move across the face of the sun (depending on idiosynchracies of the orbits). My sun dial doesn't show seconds.

Larry
DevilHorse

[-jk]

I'll try to fit my answers to your follow ons..

a') the six months apart example for parallax was for nearby stars in our galaxy (only) because they don't tend to move over 6 months. [it doesn't work for anything else astronomical like galaxies or far off stars within our galaxy]. For Venus, and Mercury, they move very fast relative to earth observations, so taking the measurements on Earth are time sensitive. But taking them at the same (approximate time, at different vertical (latitudes) gives us the geometry for our solar system that we would need.

b') the transit of a planet by the sun HAS TO be approximately when the planet is at its nearest point to us in its orbit, but not necessarily when the Earth is at its nearest point in its orbit; it is at anytime in the Earth's orbit.. right. At any time in the Earth's orbit, Venus could eclipse/transit the sun, and that makes it approximately 0 degrees with our line of sight with the sun. It is the difference between the approximately and the absolute that makes this work. Both orbits are ellipses (not circlular orbits), so the distance will vary of course. In the case of Mercury, the "ellipse" precesses in space; the famous "Precession of the Perihelion of Mercury" [You know what precession is.. it is what happens to a top when it loses steam and wobbles before it falls] that was observed since Newton's time, but only explained by Einstein's General Relativity (see https://aether.lbl.gov/www/classes/p...ionMercury.htm)... but I digress.

c') yes, I think you have it. Remember, since Galileo's time, the points of light in the sky became disks that had areas. People could look at tops and bottoms. Once they could resolve these things, then geometries and measurements could be made to Copernicus's decentralized solar system. Exciting stuff! Back then, they were really excited about different ways to measure the diameter of the earth (Kyrie missed that one in the history books). So it was natural to look out to the stars (the planets being the closest of those celestial bright things).

d') As mentioned in a', yes times did make a difference for planets that move fast. Perhaps not by the day, but by the hour if you wanted significant digits and you were not along the same meridian. It takes Venus 3 to 7 hours to move across the face of the sun (depending on idiosynchracies of the orbits). My sun dial doesn't show seconds.

Larry
DevilHorse

I think you're gonna need a bigger sundial!

Thanks for the various explanations.

-jk

[DevilHorse]

I think you're gonna need a bigger sundial!

Thanks for the various explanations.

-jk

I could get a bigger sundial, but I couldn't take my wrist anywhere

Anytime I can help..

Larry
DevilHorse

[camion]

I've been racking my brain for a different answer so here you go.

What is the first first man-made device that was solar powered?

Sundial??

[DevilHorse]

I've been racking my brain for a different answer so here you go.

What is the first first man-made device that was solar powered?

Sundial??

If casting a shadow is "powered" then I'd have to go with Stonehenge.

Greenhouses, or houses create heat for living, so is a house a device? Is a window/glass OK?

Glass and glasses/lenses have been around for a long time, and they are light powered. Really the only source of light, other stars and fire, is the sun, so any glass thing would fit the bill I'd think.

Just spitballing.

Larry
DevilHorse

[DevilHorse]

So here is a recent time lapsed picture of the Orion Nebula from NASA:
orionWsats.jpg
I had a bad feeling when I saw Starlink putting all of those satellites up in space. And in general, I applaud Elon Musk's entrepreneurial accomplishments, but who is pointing out to him that he is stepping on some some scientific toes? I know that NASA depends on SPACE-X to deliver astronauts and equipment to space, but he is also polluting the the skies for astronomers like nobody else has ever done. Where will it end? What's next?

Larry
DevilHorse

[-jk]

So here is a recent time lapsed picture of the Orion Nebula from NASA:
orionWsats.jpg
I had a bad feeling when I saw Starlink putting all of those satellites up in space. And in general, I applaud Elon Musk's entrepreneurial accomplishments, but who is pointing out to him that he is stepping on some some scientific toes? I know that NASA depends on SPACE-X to deliver astronauts and equipment to space, but he is also polluting the the skies for astronomers like nobody else has ever done. Where will it end? What's next?

Larry
DevilHorse

I guess we'll need to do space based telescopes. Or a lot of post-exposure cleanup.

Can he make his satellites less shiny? Black matte?

-jk