Search found 47 matches

by hamilton1
Wed Sep 16, 2020 9:54 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Biomarker Phosphine Discovered in of... (2020 Sep 15)
Replies: 41
Views: 9562

Re: APOD: Biomarker Phosphine Discovered in of... (2020 Sep 15)

Chris Peterson wrote: Wed Sep 16, 2020 4:21 am Life has been created in the lab from scratch.
I thought trolling was not allowed on here...
by hamilton1
Tue Jul 14, 2020 4:24 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Comet NEOWISE over Stonehenge (2020 Jul 14)
Replies: 28
Views: 8930

Re: APOD: Comet NEOWISE over Stonehenge (2020 Jul 14)

Comet NEOWISE has been rising before Sunrise in the Northeast. Comet NEOWISE will now be setting after Sunset in the Northwest. Actually the comet is circumpolar for many of us far enough north. Of course, even circumpolar objects "rise" and "set" in this context. I don't think ...
by hamilton1
Tue Jul 14, 2020 11:28 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Comet NEOWISE over Stonehenge (2020 Jul 14)
Replies: 28
Views: 8930

Re: APOD: Comet NEOWISE over Stonehenge (2020 Jul 14)

neufer wrote: Tue Jul 14, 2020 10:37 am
Prof Greg Parker wrote: Tue Jul 14, 2020 7:05 am
Should that be North East???
Comet NEOWISE has been rising before Sunrise in the Northeast.

Comet NEOWISE will now be setting after Sunset in the Northwest.
Actually the comet is circumpolar for many of us far enough north.
by hamilton1
Tue Jul 07, 2020 1:25 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Comet NEOWISE over Lebanon (2020 Jul 07)
Replies: 12
Views: 5034

Re: APOD: Comet NEOWISE over Lebanon (2020 Jul 07)

Has anyone been able to see this comet with your own eyes yet? A lot depends on your location. From rural skies the comet was reported as 'easily visible' with the naked eye (by Nick James of the BAA) whereas from less favored locations it requires averted vision. Photographs will give a somewhat m...
by hamilton1
Thu Aug 22, 2019 9:27 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Orion You Can Almost See (2019 Aug 21)
Replies: 14
Views: 7747

Re: APOD: The Orion You Can Almost See (2019 Aug 21)

The description says the Belt stars are all about 1500 LY away, but according to Jim Kaler's 'Stars' Alnilam is 1.5 times farther away than the other two - http://stars.astro.illinois.edu/sow/alnilam.html I've seen that discrepancy on other sites too. The reason for the discrepancy is the Hipparcos...
by hamilton1
Wed Aug 21, 2019 10:06 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Orion You Can Almost See (2019 Aug 21)
Replies: 14
Views: 7747

Re: APOD: The Orion You Can Almost See (2019 Aug 21)

The description says the Belt stars are all about 1500 LY away, but according to Jim Kaler's 'Stars' Alnilam is 1.5 times farther away than the other two -

http://stars.astro.illinois.edu/sow/alnilam.html

I've seen that discrepancy on other sites too.
by hamilton1
Wed Nov 21, 2018 11:05 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Unexpected Trajectory of... (2018 Nov 20)
Replies: 49
Views: 10662

Re: APOD: The Unexpected Trajectory of... (2018 Nov 20)

That assertion by itself makes no sense, since any delta-V is determined by momentum, not mass. If one knows the albedo of an asteroid/comet then one has a rough idea of its temperature at any given time. Assuming the jets are primarily water vapor then one know the average velocity/momentum of a w...
by hamilton1
Wed Nov 21, 2018 11:55 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Unexpected Trajectory of... (2018 Nov 20)
Replies: 49
Views: 10662

Re: APOD: The Unexpected Trajectory of... (2018 Nov 20)

It's a very, very low level of outgassing required to produce this extremely small deviation in orbit. There seems to be confusion about this. The Gemini North astronomers have described the non-gravitational acceleration as 'remarkably strong' There's nothing confusing. The actual force can be ver...
by hamilton1
Tue Nov 20, 2018 6:13 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Unexpected Trajectory of... (2018 Nov 20)
Replies: 49
Views: 10662

Re: APOD: The Unexpected Trajectory of... (2018 Nov 20)

It's a very, very low level of outgassing required to produce this extremely small deviation in orbit. There seems to be confusion about this. The Gemini North astronomers have described the non-gravitational acceleration as 'remarkably strong' - http://adsabs.harvard.edu/abs/2018DPS....5030102D an...
by hamilton1
Tue Nov 20, 2018 12:17 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: The Unexpected Trajectory of... (2018 Nov 20)
Replies: 49
Views: 10662

Re: APOD: The Unexpected Trajectory of... (2018 Nov 20)

Lol, NASA have had to disable comments on the youtube video. It's never aliens...
by hamilton1
Sun Jun 17, 2018 10:12 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Mars Engulfed (2018 Jun 17)
Replies: 14
Views: 10612

Re: APOD: Mars Engulfed (2018 Jun 17)

Wasn't it in 2001 that Mars was especially close to the Earth? And lots and lots of amateurs were looking forward to the opportunity of taking sharp images of the Martian surface features? And then everything was just blotted out by the planet-wide dust storm? If this ringside view of a global Mart...
by hamilton1
Wed Apr 11, 2018 11:20 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Replies: 32
Views: 59508

Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)

moontrail wrote: Wed Apr 11, 2018 10:58 am In the explanation given I miss the info about how far it`s supossed to be.
9 billion light years, I believe.
by hamilton1
Tue Jan 09, 2018 12:19 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Bright Planetary Nebula NGC 7027... (2018 Jan 09)
Replies: 230
Views: 156999

Re: APOD: Bright Planetary Nebula NGC 7027... (2018 Jan 09)

First discovered in 1878? That surprises me. It is indeed easily visible in my backyard telescope so difficult to credit that everyone from the Herschels down failed to spot it. (Assuming it has not got significantly brighter over the last 150 years).
by hamilton1
Wed Nov 22, 2017 11:26 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: 'Oumuamua: Interstellar Asteroid (2017 Nov 22)
Replies: 38
Views: 16946

Re: APOD: 'Oumuamua: Interstellar Asteroid (2017 Nov 22)

"passed unusually close to the Sun for something gravitationally unbound." I've never understood how it can be that so many comets come so very close to our sun. Can anyone explain it to me? The vast vast majority of comets come nowhere near the Sun... it's because thousands of comets do ...
by hamilton1
Mon Nov 06, 2017 2:56 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)
Replies: 42
Views: 13487

Re: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)

The simplest way to determine that an incoming object is artificial would be to observe it changing velocity in a way that would be impossible for a 'natural' object. It could, for example, attempt to adjust its trajectory to use the Sun's gravity for a braking maneuver. Or, if braking was impossib...
by hamilton1
Fri Nov 03, 2017 11:32 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)
Replies: 42
Views: 13487

Re: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)

Apparently this object can expect to travel several quadrillion years before encountering another star at such close proximity. Does sound a bit suspicious...
by hamilton1
Fri Nov 03, 2017 10:09 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)
Replies: 42
Views: 13487

Re: APOD: A/2017 U1: An Interstellar Visitor (2017 Nov 03)

I wonder what speed would be necessary to zip straight past the sun instead of being forced into a 'hairpin turn'...?
by hamilton1
Fri Sep 29, 2017 11:20 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)
Replies: 29
Views: 10186

Re: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)

quote ...
Thanks for replies, looks like I jumped the gun there.
by hamilton1
Thu Sep 28, 2017 11:52 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)
Replies: 29
Views: 10186

Re: APOD: LIGO-Virgo GW170814 Skymap (2017 Sep 28)

Using the American dating system to name these events is confusing for us Europeans. When I look at '170814' I think '17th August 2014' as opposed to the intended meaning. Using something like '14Aug2017' would be more appropriate, especially now that a European detector is also involved.
by hamilton1
Mon Jun 05, 2017 11:14 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Orion: Belt, Flame, and Horsehead (2017 Jun 04)
Replies: 26
Views: 22878

Re: APOD: Orion: Belt, Flame, and Horsehead (2017 Jun 04)

I still don't understand if the Orion's Belt stars, M42 and the 'Orion Molecular Cloud Complex' are all part of the same stucture or not. I've seen wildly differing distance estimates for each but it seems as though Alnilam for one is maybe twice as far away as its 'companions'.
by hamilton1
Thu Mar 09, 2017 11:29 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Centaurus A (2017 Mar 09)
Replies: 16
Views: 4833

Re: APOD: Centaurus A (2017 Mar 09)

My very favorite Galaxy for some reason.