DS Forums

 
 

Space and Astronomy Thread


Reply
Thread Tools Search this Thread
Old 28-09-2015, 23:01
TelevisionUser
Forum Member
 
Join Date: May 2004
Location: Storbritannia
Posts: 28,916
You seem to have missed the point. This is about water flowing on Mars NOW.
No I have not because the discovery of saline waters leaving streaky trails in crater gullies is several years old (15 IIRC) and we know all this already. This press conference is just a higher profile rehash of what was already known about. Saline (thus having a lower freezing point) water with the salts originating from the Martian regolith was the cause then and it is the same cause now, i.e. no change and no new knowledge.
TelevisionUser is offline   Reply With Quote
Please sign in or register to remove this advertisement.
Old 28-09-2015, 23:26
njp
Forum Member
 
Join Date: Dec 2004
Posts: 21,645
No I have not because the discovery of saline waters leaving streaky trails in crater gullies is several years old (15 IIRC) and we know all this already. This press conference is just a higher profile rehash of what was already known about. Saline (thus having a lower freezing point) water with the salts originating from the Martian regolith was the cause then and it is the same cause now, i.e. no change and no new knowledge.
I expect you'll be wanting to cite the relevant scientific papers from 15 years ago, complete with spectroscopic analysis...
njp is offline   Reply With Quote
Old 28-09-2015, 23:44
TelevisionUser
Forum Member
 
Join Date: May 2004
Location: Storbritannia
Posts: 28,916
I expect you'll be wanting to cite the relevant scientific papers from 15 years ago, complete with spectroscopic analysis...
More likely, I expect I'll be telling you that there were plenty of peer-reviewed and published papers from 2002 onwards that were already elucidating the saline water cause of the streaks in gullies on Mars following the photos taken by NASA's Mars Global Surveyor in the summer of 2000.

That orbiter, and the European Space Agency's Mars Express probe, have both made a great contribution to the study and understanding of Mars.
TelevisionUser is offline   Reply With Quote
Old 29-09-2015, 14:07
njp
Forum Member
 
Join Date: Dec 2004
Posts: 21,645
More likely, I expect I'll be telling you that there were plenty of peer-reviewed and published papers from 2002 onwards that were already elucidating the saline water cause of the streaks in gullies on Mars following the photos taken by NASA's Mars Global Surveyor in the summer of 2000.
And yet you haven't given me even one...

Isn't the point that there was a lot of speculation about the cause, but not the compelling evidence which has now been found? Unless you really think that NASA are a bunch of clowns, of course.
njp is offline   Reply With Quote
Old 29-09-2015, 16:49
TelevisionUser
Forum Member
 
Join Date: May 2004
Location: Storbritannia
Posts: 28,916
And yet you haven't given me even one...

Isn't the point that there was a lot of speculation about the cause, but not the compelling evidence which has now been found? Unless you really think that NASA are a bunch of clowns, of course.
Seek and ye shall find ------> http://www.jstor.org
TelevisionUser is offline   Reply With Quote
Old 29-09-2015, 17:15
njp
Forum Member
 
Join Date: Dec 2004
Posts: 21,645
That's rather less useful than merely pointing me at google. I note that a lot of free content concerning Mars is available there from the the late 19th and early 20th centuries, which makes quite entertaining reading.

However, I did not find that which I sought. Perhaps you could help?
njp is offline   Reply With Quote
Old 29-09-2015, 17:19
TelevisionUser
Forum Member
 
Join Date: May 2004
Location: Storbritannia
Posts: 28,916
And now for some astro news starting with a flocculent galaxy (yes, they really do exist!):

A new picture from the Hubble Space Telescope shows the spiral galaxy NGC 3521 in a shot that looks almost artificial in its painterly beauty. Discovered in 1784 by British astronomer William Herschel, the 40 million light-year distant object has what are called flocculent spirals, a softer version of the well-defined arms of other galaxies.

Lord Foster's architectural partnership has come up with some interesting new ideas for a Mars base:

http://www.dezeen.com/2015/09/25/fos...bots-regolith/

http://www.dailymail.co.uk/sciencete...ed-planet.html
TelevisionUser is offline   Reply With Quote
Old 02-10-2015, 07:33
Eddie Badger
Forum Member
 
Join Date: Apr 2009
Posts: 5,354
Latest images from Pluto's moon Charon http://www.nasa.gov/feature/pluto-s-...iolent-history
Eddie Badger is online now   Reply With Quote
Old 02-10-2015, 19:22
Keyser_Soze1
Forum Member
 
Join Date: Feb 2014
Location: The Sixth Circle of Hell
Posts: 20,174
Beat me to it.

http://phenomena.nationalgeographic....h-a-dark-past/

http://www.bbc.co.uk/news/science-environment-34420062

Why all those posters of the Solar System are utter bollocks.

http://phenomena.nationalgeographic....rong-till-now/

Remember that this is just the major Planets - the distance involved are utterly insignificant compared to what is beyond Neptune - the Kuiper Belt, Scattered Disc and all the way to the Oort cloud - it boggles the mind.
Keyser_Soze1 is offline   Reply With Quote
Old 02-10-2015, 19:44
Kapellmeister
Inactive Member
 
Join Date: Jul 2009
Location: Taedet animam meam vitae
Posts: 40,368
Why all those posters of the Solar System are utter bollocks.

http://phenomena.nationalgeographic....rong-till-now/

Remember that this is just the major Planets - the distance involved are utterly insignificant compared to what is beyond Neptune - the Kuiper Belt, Scattered Disc and all the way to the Oort cloud - it boggles the mind.
Wow, loved it, loved it, loved it! What a beautiful film. Thanks for posting
Kapellmeister is offline   Reply With Quote
Old 02-10-2015, 20:03
Keyser_Soze1
Forum Member
 
Join Date: Feb 2014
Location: The Sixth Circle of Hell
Posts: 20,174
Wow, loved it, loved it, loved it! What a beautiful film. Thanks for posting
You are welcome.
Keyser_Soze1 is offline   Reply With Quote
Old 02-10-2015, 20:33
Andrew1954
Forum Member
 
Join Date: Oct 2013
Posts: 3,994
The International Astronomy Show is still on in Warwickshire tomorrow Saturday 3rd October. So if you fancy looking at and possibly buying some serious astronomical kit - telescopes etc - I can recommend it. I went along to day and managed to keep the wallet in my pocket. But it was very interesting.
Andrew1954 is offline   Reply With Quote
Old 06-10-2015, 00:49
HenryGarten
Forum Member
 
Join Date: Jun 2006
Posts: 19,567
NASA Apollo archive put online. See Thousands of NASA Aplollo photos uploaded online
HenryGarten is offline   Reply With Quote
Old 06-10-2015, 03:39
Rich Tea.
Forum Member
 
Join Date: Jun 2012
Location: Newport Pagnell
Posts: 21,349
Beat me to it.

http://phenomena.nationalgeographic....h-a-dark-past/

http://www.bbc.co.uk/news/science-environment-34420062

Why all those posters of the Solar System are utter bollocks.

http://phenomena.nationalgeographic....rong-till-now/

Remember that this is just the major Planets - the distance involved are utterly insignificant compared to what is beyond Neptune - the Kuiper Belt, Scattered Disc and all the way to the Oort cloud - it boggles the mind.
I love these kind of tasks.

For example, I know that our nearest neighbouring galaxy is Andromeda at 2.5 million light years distance. But what if we were to make our own Milky Way down to the size of a marble. How far away would the Andromeda marble be from the Milky Way one?
Rich Tea. is offline   Reply With Quote
Old 06-10-2015, 06:18
Carlos_dfc
Forum Member
 
Join Date: May 2002
Location: Bishop-Auckland / Darlington
Posts: 6,636
....what if we were to make our own Milky Way down to the size of a marble. How far away would the Andromeda marble be from the Milky Way one?
Well if our galaxy (approx 100,000 lt.yrs. diameter) was the size of a marble (about half an inch diameter).....

Andromeda galaxy would be about a foot away from us.
M33 (the Triangulum galaxy) would be a smaller marble... maybe 13-14 inches away from us, and about 3½ - 4 inches from Andromeda.
Carlos_dfc is offline   Reply With Quote
Old 06-10-2015, 20:29
Keyser_Soze1
Forum Member
 
Join Date: Feb 2014
Location: The Sixth Circle of Hell
Posts: 20,174
Well if our galaxy (approx 100,000 lt.yrs. diameter) was the size of a marble (about half an inch diameter).....

Andromeda galaxy would be about a foot away from us.
M33 (the Triangulum galaxy) would be a smaller marble... maybe 13-14 inches away from us, and about 3½ - 4 inches from Andromeda.
A more interesting question would be if the earth was the size of a marble then how big would the Milky Way be?

I am sure someone, somewhere will have calculated something similar at one time or another.
Keyser_Soze1 is offline   Reply With Quote
Old 06-10-2015, 22:14
Rich Tea.
Forum Member
 
Join Date: Jun 2012
Location: Newport Pagnell
Posts: 21,349
Well if our galaxy (approx 100,000 lt.yrs. diameter) was the size of a marble (about half an inch diameter).....

Andromeda galaxy would be about a foot away from us.
M33 (the Triangulum galaxy) would be a smaller marble... maybe 13-14 inches away from us, and about 3½ - 4 inches from Andromeda.
A more interesting question would be if the earth was the size of a marble then how big would the Milky Way be?

I am sure someone, somewhere will have calculated something similar at one time or another.
Not long after I posted that question last night I thought about it and the answer was rather closer than first imagined and ridiculously simple to work out when you know the 100,000 light year length. Doh! Clearly just about 12 inches or so! Not too impressive in the grand scale of things.

Here's a good one regarding our Milky Way being just an inch across, then how far would the edge of the visible universe be in comparison.

http://www.astronomycafe.net/qadir/q2139.html
Rich Tea. is offline   Reply With Quote
Old 06-10-2015, 23:09
Rich Tea.
Forum Member
 
Join Date: Jun 2012
Location: Newport Pagnell
Posts: 21,349
If our Sun was an inch in diameter then Proxima Centauri our nearest star at just over 4 light years distance would be 453 miles away to scale. You can imagine, or not, just how big that would make the whole Milky Way galaxy in that case.
Rich Tea. is offline   Reply With Quote
Old 07-10-2015, 00:01
atg
Forum Member
 
Join Date: Nov 2008
Location: London
Posts: 4,020
I did once work out that on the basis of the Sun being a grain of sand 1mm in diameter, Neptune's orbit is a few metres across, the nearest star is another grain of sand 15 miles away, and the milky way then fits comfortably inside the orbit of the moon.

These things are interesting to work out, quite illuminating about the scale of the universe.
atg is offline   Reply With Quote
Old 07-10-2015, 08:05
Heston Veston
Forum Member
 
Join Date: Mar 2013
Posts: 3,063
Originally Posted by Keyser Soze
A more interesting question would be if the earth was the size of a marble then how big would the Milky Way be?
Earth diameter = 1.2e7m, galaxy diameter = 9.5e20m, so for a half-inch marble earth the galaxy is then 10e12 metres, or a bit less than the orbit of Jupiter.

The sun is a 5 foot sphere, 170 yards away.

(caveat - calculated in a hurry, may not be accurate)
Heston Veston is offline   Reply With Quote
Old 07-10-2015, 22:15
WhatJoeThinks
Forum Member
 
Join Date: Sep 2011
Posts: 10,220
Mysterious Ripples Found Racing Through Planet-Forming Disk

Interesting dynamics puzzle. It might be a while before we hear the solution though.
WhatJoeThinks is offline   Reply With Quote
Old 07-10-2015, 22:27
gkec
Forum Member
 
Join Date: Oct 2011
Posts: 492
I love these kind of tasks.

For example, I know that our nearest neighbouring galaxy is Andromeda at 2.5 million light years distance. But what if we were to make our own Milky Way down to the size of a marble. How far away would the Andromeda marble be from the Milky Way one?
As the milky way / Andromeda galaxy are roughly 100,000 light years across then 25 marble widths apart.
Another way of looking at this is that the Andromeda galaxy is approximately 100,000 light years across. So taking the distance of 2.5 million light years the apparent size of Andromeda galaxy in the sky is the same as viewing a meter ruler at 25 meters. In other words quite big. Bigger than the moon. It's just very faint.
gkec is offline   Reply With Quote
Old 07-10-2015, 23:46
Carlos_dfc
Forum Member
 
Join Date: May 2002
Location: Bishop-Auckland / Darlington
Posts: 6,636
....the apparent size of Andromeda galaxy in the sky is.....
.......Bigger than the moon.
Yes - the Moon is approximately half a degree across (as is the Sun)
The Andromeda galaxy is somwhere in the region of 3 degrees across.
It's dim, but still bright enough to be seen by naked eye from a rural site - and the best way to see it with your eyes (as opposed to a photo) is to use large aperture binoculars with relatively low magnification.
It's far too large to fit into the field of view of any telescope big enough to give a decent image. (A telescope at even a low magnification of, say, 30x, will typically have a field of view diameter of only about 1½ degrees or so)

My own personal best VISUAL observations have been through 20x80 binoculars, with a 3.8º FOV - Under a good dark sky it almost fills the field.
Carlos_dfc is offline   Reply With Quote
Old 14-10-2015, 20:18
Eddie Badger
Forum Member
 
Join Date: Apr 2009
Posts: 5,354
Cassini about to get up close and personal to Enceladus
http://www.nasa.gov/press-release/ca...moon-enceladus
Eddie Badger is online now   Reply With Quote
Old 17-10-2015, 19:26
HenryGarten
Forum Member
 
Join Date: Jun 2006
Posts: 19,567
Interesting article about one of the only two remaining S-IC Saturn V first stages

Plan to move it and preserve it.
HenryGarten is offline   Reply With Quote
 
Reply




 
Forum Jump


All times are GMT. The time now is 18:43.