Search found 18398 matches
- Wed Dec 29, 2021 4:18 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
- Replies: 48
- Views: 21297
Re: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
Pon - Thank you very much for the time and care you've spent following the posts, clarifying and correcting our understanding of your images, and sharing your many years of experience recording and figuring out the plume(s). For us, one APOD sometimes does not tell enough information, and for sever...
- Wed Dec 29, 2021 3:56 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Giant Storms and High Clouds on Jupiter (2021 Dec 29)
- Replies: 11
- Views: 3079
Re: APOD: Giant Storms and High Clouds on Jupiter (2021 Dec 29)
Have we figured out the composition of these 'clouds' yet ? https://upload.wikimedia.org/wikipedia/commons/f/f5/Structure_of_Jovian_atmosphere.png <<The lowest Jupiter atmospheric layer, the troposphere, has a complicated system of clouds and hazes, comprising layers of ammonia, ammonium hydrosulfi...
- Tue Dec 28, 2021 7:38 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
- Replies: 48
- Views: 21297
- Tue Dec 28, 2021 7:31 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Sun Halo over Sweden (2021 Dec 28)
- Replies: 8
- Views: 2928
- Tue Dec 28, 2021 4:03 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
- Replies: 47
- Views: 14134
Re: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
------------------------------------------------------------------------------------------- MCC1b : Mid Course Correction Burn 1b Nominal Event Time: Launch + 2 days <<This burn fine-tunes Webb's trajectory after launch. The duration of the burn will depend on Ariane 5 launcher performance. There a...
- Mon Dec 27, 2021 10:25 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
- Replies: 48
- Views: 21297
Re: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
The JWST itself ( not the Ariane ) was supposed to have its first burn at around launch time plus 12 hours (i.e., just prior to sunrise at the Thai National Observatory in Doi Inthanon National Park). Since burns are most effective near perigee (i.e., maximum velocity) presumably the JWST has almos...
- Mon Dec 27, 2021 8:31 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
- Replies: 48
- Views: 21297
Re: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
The last stage of the Ariane V rocket stopped firing at about 1,000 km altitude over East Africa and might possibly have still been seen some 30º (= cos -1 [R/(1000+R)]) further East. So is this a composite of a photo of the launch plume of the Ariane V rocket taken (from Africa?) somehow Thai'd in...
- Mon Dec 27, 2021 4:08 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
- Replies: 47
- Views: 14134
Re: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
it seems odd to me that they would jettison the protective fairing covering the scope so soon. The announcer said that then required them to keep "shimmying" or rotating the vehicle a little to keep the exposed mirror segments out of the sun. So, was the reason for jettisoning the fairing...
- Mon Dec 27, 2021 3:56 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
- Replies: 48
- Views: 21297
Re: APOD: Comet Leonard behind JWST Launch Plume (2021 Dec 27)
Explanation: In contrast, the upper streak is the launch plume of the Ariane V rocket that lifted the James Webb Space Telescope (JWST) off the Earth two days ago. The featured single-exposure image was taken from Thailand , and the foreground spire is atop a pagoda in Doi Inthanon National Park .>...
- Sun Dec 26, 2021 5:32 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
- Replies: 47
- Views: 14134
e: APOD: James Webb Space Telescope over Earth (2021 Dec 26)
https://www.youtube.com/watch?v=RzGLKQ7_KZQ Current Deployment Step : Gimbaled Antenna Assembly Nominal Event Time: Launch + 1 day The Gimbaled Antenna Assembly (GAA) holds Webb's high rate antenna. It is rotated to its parked position pointed back to the Earth. This is an 'automatic' deployment as...
- Sun Dec 26, 2021 2:56 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: M1: The Crab Nebula (2021 Dec 24)
- Replies: 18
- Views: 4721
Re: APOD: M1: The Crab Nebula (2021 Dec 24)
I don't see the pulsar. There's several bright spots. It's the bright spot blinking 30 times a second: https://www.youtube.com/watch?v=UQSUNMDJ5GI https://upload.wikimedia.org/wikipedia/commons/e/e5/Titan_transits_Crab_Nebula_2003.jpg <<On January 5, 2003, Titan — Saturn's largest moon and the only...
- Sat Dec 25, 2021 7:59 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Tail of a Christmas Comet (2021 Dec 25)
- Replies: 9
- Views: 3579
Re: APOD: The Tail of a Christmas Comet (2021 Dec 25)
https://www.youtube.com/watch?v=YXjPgDol2jE Nice comet. Sort of off topic but nobody has mentioned it yet. The James Webb telescope was successfully launched this morning from French Guiana. It will take 12 to 14 days for it to unfurl its solar panels and sun shield so everybody at NASA and some 16...
- Sat Dec 25, 2021 6:09 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: James Webb Space Telescope (JWST)
- Replies: 104
- Views: 91136
MIRI Xmas!
Things We've Never Seen 8-) https://www.youtube.com/watch?v=pVKzZ89N2Ks https://www.youtube.com/watch?v=cp_7AJseYYc <<MIRI (Mid-InfraRed Instrument) will measure the mid-to-long-infrared wavelength range from 5 to 27 micrometers. It contains both a mid-infrared camera and an imaging spectrometer. M...
- Sat Dec 25, 2021 5:53 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Tail of a Christmas Comet (2021 Dec 25)
- Replies: 9
- Views: 3579
Re: APOD: The Tail of a Christmas Comet (2021 Dec 25)
(of course, the comet might still be reasonably seen as in a near Keplerian elliptical orbit around the center of the galaxy). Keplerian elliptical orbits require a 1/R 2 force field. Milky Way dark matter, however, produces an approximate 1/R force field [= a logarithmic potential] which balances ...
- Fri Dec 24, 2021 3:36 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: M1: The Crab Nebula (2021 Dec 24)
- Replies: 18
- Views: 4721
Re: APOD: M1: The Crab Nebula (2021 Dec 24)
Would 12 light years [wide] have engulfed any nearby stars ? And what would be the effect ? Would they even notice ? The nebula probably encloses other stars. Anybody on those stars would have certainly experienced effects from the supernova. But the expanding nebula, from the inside, would just ma...
- Fri Dec 24, 2021 2:15 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: M1: The Crab Nebula (2021 Dec 24)
- Replies: 18
- Views: 4721
Re: APOD: M1: The Crab Nebula (2021 Dec 24)
Click to play embedded YouTube video.
VictorBorun wrote: ↑Fri Dec 24, 2021 9:11 am
and why is the Crab so complicated?
Why cannot we see just a pair of long jets along the axis of the "neutron star spinning 30 times a second" and some disk of a less radius in the equatorial plane?
- Thu Dec 23, 2021 9:26 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Three Planets and a Comet (2021 Dec 23)
- Replies: 13
- Views: 5744
Re: APOD: Three Planets and a Comet (2021 Dec 23)
I donate half the earnings I make from my postings
on The Starship Asterisk* to The Human Fund.
- Thu Dec 23, 2021 9:10 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Launch of the IXPE Observatory (2021 Dec 22)
- Replies: 11
- Views: 4854
Re: APOD: Launch of the IXPE Observatory (2021 Dec 22)
I still don't understand the statement about the ripples: "The ripples were discrete, so there wasn't a lot of interaction to produce a blur that you might be used to seeing." What would the reflection look like if the water was a solid mirror instead? Wouldn't it be just as blurry as the...
- Thu Dec 23, 2021 8:39 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Dance of Venus and Earth (2020 Jun 03)
- Replies: 28
- Views: 11077
APOD: The Dance of Venus and Earth (2020 Jun 03)
Because we have a very, very good understanding of the underlying science involved in orbital dynamics. There are many examples of coincidental near orbital resonances throughout the Solar System. They are expected to occur based on simple statistics, and the observed probabilities are consistent w...
- Thu Dec 23, 2021 8:31 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Three Planets and a Comet (2021 Dec 23)
- Replies: 13
- Views: 5744
Re: APOD: Three Planets and a Comet (2021 Dec 23)
What's the red spot to the left of the comet? That was a plane, moving a short distance during the 4-second exposure. - Tunç Tezel https://www.youtube.com/watch?v=xteXgurD-DM <<In quantum field theory, the Casimir effect is a physical force acting on the macroscopic boundaries of a confined space w...
- Thu Dec 23, 2021 4:56 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Three Planets and a Comet (2021 Dec 23)
- Replies: 13
- Views: 5744
Re: APOD: Three Planets and a Comet (2021 Dec 23)
Neufer, that's a nice gift for a non astronomer like me, but who watches a lot of space shows on TV like Star Trek. Three of my favorite television actors appeared in that film. My favorite is Tom Selleck who in my opinion can do no wrong. https://www.youtube.com/watch?v=ppGd-2nEOVQ None that he wo...
- Thu Dec 23, 2021 4:31 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: The Dance of Venus and Earth (2020 Jun 03)
- Replies: 28
- Views: 11077
APOD: The Dance of Venus and Earth (2020 Jun 03)
The near orbital resonance is just a coincidence. But that same near resonance might play a role in the orbital-rotational relationship that seems to keep the same place on the surface rotating into the same position at each inferior conjunction... meaning the latter might not be a coincidence at a...
- Thu Dec 23, 2021 3:36 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Three Planets and a Comet (2021 Dec 23)
- Replies: 13
- Views: 5744
Re: APOD: Three Planets and a Comet (2021 Dec 23)
Explanation: Are you still looking for that perfect holiday gift for an astronomer? ... In this snapshot of the December solstice evening sky from the village of Kirazli, Turkey the brightest celestial beacon is Venus, close to the southwestern horizon at the right. Look left and up to find Saturn ...
- Thu Dec 23, 2021 3:18 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Solstice Sun and Milky Way (2021 Dec 21)
- Replies: 11
- Views: 4964
Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)
Today's APOD reminded me of a recent post . I was curious if we were high enough above the plane to notice the broad disc – minus the dust clouds ? After time to pause, I’m pretty sure I’m not high enough to notice. 8-) But that sun sure is bright! :yes: The disk thickness is ~1% (~1000 ly) of the ...
- Wed Dec 22, 2021 4:41 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Solstice Sun and Milky Way (2021 Dec 21)
- Replies: 11
- Views: 4964
Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)
Click to play embedded YouTube video.