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  1. #441
    Join Date
    Feb 2007
    Location
    Steamboat Springs, CO
    Quote Originally Posted by DevilHorse View Post
    We've touched on the subject of light pollution from the many satellites from the Elon Musk Starlink venture.

    Many of you have no doubt also seen the movie Gravity with Sandra Bullock, where a collision in space creates a huge amount of space debris that causes a huge calamity for an astronaut crew.

    Well yesterday that narrative appeared to be happening for real.
    https://www.space.com/space-debris-a...-november-2021
    The russians were apparently testing an Anti-Satellite (ASAT) space weapon and attempted to shoot down one of their own satellites. Of course, these things don't get destroyed in a lump and fall to earth; they become a large debris field that orbits the earth in a thousand small, fast moving shards.

    The 7 astronauts on the International Space Station had to take cover as it moved through the debris field. But it will not be a one time event unless the ISS is moved to a different orbit to avoid this (now) 'permanent' debris field.

    Larry
    DevilHorse
    I thought the entertaining movie, Gravity, broke the laws of physics. Projective-velocity debris was endangering Bullock and Co. every 90 minutes. I mean -- really? If debris field going much faster than the satellite/space ship in orbit, then that stuff would move to an outer orbit -- or leave Earth's gravitational field entirely. Or, maybe I got less from Physics 125 than I thought.
    Sage Grouse

    ---------------------------------------
    'When I got on the bus for my first road game at Duke, I saw that every player was carrying textbooks or laptops. I coached in the SEC for 25 years, and I had never seen that before, not even once.' - David Cutcliffe to Duke alumni in Washington, DC, June 2013

  2. #442
    Quote Originally Posted by sagegrouse View Post
    I thought the entertaining movie, Gravity, broke the laws of physics. Projective-velocity debris was endangering Bullock and Co. every 90 minutes. I mean -- really? If debris field going much faster than the satellite/space ship in orbit, then that stuff would move to an outer orbit -- or leave Earth's gravitational field entirely. Or, maybe I got less from Physics 125 than I thought.
    You're making an assumption that the orbit is approximately circular, at the same height, and perhaps equatorial (after the Russian rocket, who knows what the orbit of the center of mass is). If we're talking about the Gravity case, where everything is situated around the equator (and the ellipse is about circular), I agree that space junk would not be able to sustain the orbit, at the same radius and speed. Velocity of an object in an orbit gets slower with a greater radius; you can't have 2 things with 2 different speeds having the same 'circular' orbit around the earth. Mass of the orbiting object (around the earth) does not matter; only the position and velocity of the object in its orbit for it to be sustained.

    For the Russian exploded satellite case, if the orbit was no longer circular and became more elliptical [eccentric is the mathematical term] (further out at some times and closer to earth at others) it would cross paths with a circular orbit and have some significant velocity while doing it. Additionally, I'd expect the debris field to continually expand and disburse; gravity and cohesion effects would be almost nothing. For geosynchronous satellites, orbits along the equator makes sense. For the International Space Station, it does not; the ISS is MUCH closer to earth (by about 100 times) and does not move along (parallel to) the equator at all. The ISS pattern across earth looks more like a lissajous figure (devotees of the original Outer Limits know what this looks like).

    With any of these satellites, space stations, the relative differences in their speeds is so significant that the debris field of one (given that it was blown up) relative to the other is extreme because it was in a different orbit. I don't know the ongoing issues with the Russian blast, but I was surprised that the issue with the ISS presented itself so soon after the Russian missile hit its satellite. Either large pieces of that satellite are expected to fall to earth or this will be a re-occurring problem for a very long time. Not much further information has been mentioned beyond the initial ISS encounter.

    Larry
    DevilHorse

  3. #443
    An interesting article on Space Debris:
    https://thedispatch.com/p/the-rising...f-space-debris

    Here is the Wikipedia entry on Kessler Syndrome and collisional cascading:
    https://en.wikipedia.org/wiki/Kessler_syndrome

    Larry
    DevilHorse

  4. #444
    If you really want an overload of information on the Russian exploded satellite incident, here is an excellent twitter feed from Astronomer Johnathon McDowell:
    https://twitter.com/planet4589

    Here are a few interesting panels:

    Shows that in a few years many of the Russian satellite pieces will fall into the atmosphere of earth:
    https://pbs.twimg.com/media/FERFub5X...png&name=small

    Red line shows danger area for collision with debris:
    https://pbs.twimg.com/media/FEQ5yVRX...jpg&name=small

    Blue line shows height of the Russian satellite, Red line shows height of the ISS. Russian satellite has no rocket to control its' height (obviously degrading); ISS has some control, but there are other hazards that it is trying to avoid.
    https://pbs.twimg.com/media/FEPs0sBW...jpg&name=small

    "This plot shows the separation between Ikar 39 and the ISS - the satellite itself never comes closer than 1000 km. BUT if the sat broke up, the same will not be true of resulting debris" Note that the peaks are every 93 minutes!!!
    https://pbs.twimg.com/media/FEPlHbCX...jpg&name=small

    Investigate the twitter feed for other interesting plots, and there are daily/hourly updates. Cool stuff and also about Starlink.

    Larry
    DevilHorse
    Last edited by DevilHorse; 11-19-2021 at 09:03 AM.

  5. #445
    Join Date
    Nov 2007
    Location
    Vermont
    Had a few good peeks at the lunar eclipse in the middle of the night, right outside the bedroom window.

  6. #446
    Join Date
    Feb 2007
    Location
    Washington, DC area

  7. #447
    Quote Originally Posted by -jk View Post
    Here's an article written in 2013 about the Hubble (serviced about 3 years before):
    http://www.cbsnews.com/network/news/...ac6a3-588.html

    It mentions the James Webb Telescope targeted for 2018 (due next month, now 3 years late).

    It also mentions that it expects the Hubble to be working into the 2020 year... Uh oh.
    Not sure when the liquid helium will evaporate on the sensitive detectors.

    The limiting factor apparently is how long the hydrazine fuel that keeps the Hubble up in space will be the limiting factor before the helium runs out.
    Hubble is expected to crash back to earth in the 2030 - 2040 timeframe. . Whew.

    Speaking of working well beyond the original engineering, Ingenuity has done its 15th flight and is working on #16. Amazing!

    Larry
    DevilHorse

  8. #448

    DART

    If you're staying up late on Thanksgiving, the DART mission (to hit an asteroid with a missile to 'practice' deflection) is planned to take off at 1:20 on Friday morning EST.
    https://www.space.com/nasa-dart-aste...ssion-webcasts

    Start shifting your sleep pattern for the Gonzaga game.

    Larry
    DevilHorse

  9. #449
    Quote Originally Posted by DevilHorse View Post
    If you're staying up late on Thanksgiving, the DART mission (to hit an asteroid with a missile to 'practice' deflection) is planned to take off at 1:20 on Friday morning EST.
    https://www.space.com/nasa-dart-aste...ssion-webcasts

    Start shifting your sleep pattern for the Gonzaga game.

    Larry
    DevilHorse
    DART successfully took off, and will attempt to deflect the Didymos moonlet in the fall.
    https://www.cbsnews.com/news/nasa-pr...on-initiative/

    ScreenHunter_01 Nov. 24 07.50.jpg

    Larry
    DevilHorse

  10. #450
    Here is an interesting exoplanet:

    https://www.bbc.co.uk/newsround/59330620

    http://www.sci-news.com/astronomy/in...89b-09814.html


    TOI 1789b is a super-Jupiter, 2000 degrees (Kelvin) [300 degrees Kelvin is about room temperature]. This exoplanet circles around it's star every 3 days!!!

    TOI 1789b has a mean orbital radius of 0.05AU (Astronomical Units, where 1 AU is earth's 93 million miles).

    For comparison, Mercury has about a 0.38 AU with an 88 day year (orbital period).

    Assuming it is a gas giant (why wouldn't it be with that mass), what is the physical shape?
    It has to be the shape of an egg/ellipsoid... very eccentric. Wow!!

    Larry
    DevilHorse

  11. #451
    Join Date
    Feb 2008
    Location
    New Bern, NC unless it's a home football game then I'm grilling on Devil's Alley
    Has anyone been out to see Leonard yet? It seems like the coolest stuff always shows up at the worst hours, in this case like 4am, but it looks like an amazing comet. I'm going to bite the bullet this weekend as long as skies are clear, and take my telescopes out in hopes of getting a photo or two.

    https://www.usatoday.com/story/news/...er/8811373002/
    Q "Why do you like Duke, you didn't even go there." A "Because my art school didn't have a basketball team."

  12. #452
    Quote Originally Posted by CameronBornAndBred View Post
    Has anyone been out to see Leonard yet? It seems like the coolest stuff always shows up at the worst hours, in this case like 4am, but it looks like an amazing comet. I'm going to bite the bullet this weekend as long as skies are clear, and take my telescopes out in hopes of getting a photo or two.

    https://www.usatoday.com/story/news/...er/8811373002/
    I was out at noon today.. nuthin.

    Larry
    DevilHorse

  13. #453
    Join Date
    Feb 2008
    Location
    New Bern, NC unless it's a home football game then I'm grilling on Devil's Alley
    Quote Originally Posted by DevilHorse View Post
    I was out at noon today.. nuthin.

    Larry
    DevilHorse
    Stupid sun...always in the way!
    Q "Why do you like Duke, you didn't even go there." A "Because my art school didn't have a basketball team."

  14. #454
    Zoom into (the middle) to this picture from Perseverance and what do you see?
    https://pbs.twimg.com/media/FFpZVL0X...jpg&name=small

    Close up:
    https://pbs.twimg.com/media/FFpgEL9U...g&name=240x240

    Larry
    DevilHorse

  15. #455
    Quote Originally Posted by CameronBornAndBred View Post
    Has anyone been out to see Leonard yet? It seems like the coolest stuff always shows up at the worst hours, in this case like 4am, but it looks like an amazing comet. I'm going to bite the bullet this weekend as long as skies are clear, and take my telescopes out in hopes of getting a photo or two.

    https://www.usatoday.com/story/news/...er/8811373002/
    Went out this morning at 5:10am. Had decent viewing conditions. Looked between Ursa Major and Bootes. Could not find Leonard.
    Used high powered binoculars. Expanded the search and scanned most of the quadrant.
    Did find Waldo, Carmen San Diego, a few Klingons though.

    Larry
    DevilHorse

  16. #456

    "All These Worlds Are Yours, But Hands Off Europa!!!"

    I recall last year when NASA selected 2 out of 4 missions, both going to Venus and the losers were the trips to Io and Triton.

    What I didn't notice was that NASA had contracted with Elon Musk's SpaceX to send a probe over Europa to look for life. The Europa Clipper is targeted for launch in October 2024:
    https://en.wikipedia.org/wiki/Europa_Clipper
    https://www.planetary.org/space-missions/europa-clipper

    It will use the Falcon Heavy booster to get the payload out into space, it looks like it would take 5.5 years of a gravity assisted flight to get it to where it needs to go.

    Larry
    DevilHorse

  17. #457
    Saturday morning should be the last chance to catch Comet Leonard as a morning comet. On December 12th, the comet gives its closest approach, and switches to being an evening comet. I just got a new flash that Leonard is now visible to the naked eye, so it is certainly visible with binoculars. Weather has been limiting for me, so no chance. Certainly, the tail will get a little larger as it approaches the sun, but it isn't getting much closer.

    Good luck.

    Larry
    DevilHorse

  18. #458
    Join Date
    Feb 2008
    Location
    New Bern, NC unless it's a home football game then I'm grilling on Devil's Alley
    Quote Originally Posted by DevilHorse View Post
    Saturday morning should be the last chance to catch Comet Leonard as a morning comet. On December 12th, the comet gives its closest approach, and switches to being an evening comet. I just got a new flash that Leonard is now visible to the naked eye, so it is certainly visible with binoculars. Weather has been limiting for me, so no chance. Certainly, the tail will get a little larger as it approaches the sun, but it isn't getting much closer.

    Good luck.

    Larry
    DevilHorse
    Rain here, so I'm out of luck. And we might never see it again.
    Reports are that it is fading, even though it is getting closer, which isn't good news if you are a comet. It's possible that it is breaking up, or falling under a couple of other less than optimal scenarios.
    Q "Why do you like Duke, you didn't even go there." A "Because my art school didn't have a basketball team."

  19. #459
    Join Date
    Feb 2007
    Location
    Durham, within a couple of miles of Cameron
    Quote Originally Posted by CameronBornAndBred View Post
    Rain here, so I'm out of luck. And we might never see it again.
    Reports are that it is fading, even though it is getting closer, which isn't good news if you are a comet. It's possible that it is breaking up, or falling under a couple of other less than optimal scenarios.
    I've also been out of luck trying to see Leonard for the last week, despite some impressively clear 5-6am skies. Arcturus has been easy, but the comet has not. I *think* I have seen the comet -as a fuzzy spot- with binoculars, based on charts, etc. But getting my finder on my Celestron 8" SC to find Leonard has been unsuccessful, and doing the hand controller weave, searching for something as bright as Leonard is supposed to be, just hasn't worked.
    Hope it is brighter in the evening, but I'm skeptical that it will be high enough for my Western horizon -alas.

  20. #460
    Join Date
    Feb 2011
    Location
    Summerville ,S.C.
    Quote Originally Posted by CameronBornAndBred View Post
    I have a Celestron Astromaster 130, and have enjoyed it lots. For most of my viewing, I use my larger 8" dobsonian, but the 130 has lots of benefits that I have no doubt that your kid will enjoy. Primarily, the one you got is way easier to transport due to size and weight. The mirror is nice enough size that you can really enjoy planetary viewing, and it looks like the phone app will be helpful in finding targets. It will still take patience finding what you are looking at since it isn't computer controlled, but he will get used to it. It also looks like the mount and tripod are pretty user friendly. My Astromaster has an equatorial mount, which while having lots of advantages, can also be headache inducing. (A big reason why I love my dobsonian.)

    He's going to have fun!
    Absolutely great telescope for starter.
    He finally got to the point he can fine tune it.a few more days we will go to the beach at night. We should have access to a lot more sky.

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