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Chinahand

Astronomy Stuff

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6 minutes ago, Bobbie Bobster said:

@guzziBefore the end of this year according to some commentators.  And they have a lot more credibility than the beardy alternative.

I agree. They seem to have got it right all the way. Apologies, I hit post a bit too sharp. I've edited to add more detail and links.

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There's something special about this map of our galaxy:

ESA_Gaia_DR2_Average_Rad_Vel_1280.jpg

It is from the European Space Agency's Gaia satellite which is collecting mind bogglingly accurate measurements of the movements of billions of stars in the Milky Way.

The reds and blues in the top image are whether the star is moving towards or away from us.  Red stars are redshifted and moving away from us, blue stars are blue shifted by moving towards us.

The image is a Mollweide projection taking the 3D celestial sphere and projecting it onto a flat surface.

Just like in a map of the globe you can put the centre of the map basically anywhere - for the globe it is only convention that has 0 degrees latitude through Greenwich and the same choice was faced by the astronomers in producing their map of the Milkyway's stars where to put the centre of their image.

 

Mollweide_projection_SW.jpg

For them though the choice was easier because the galaxy does have a centre about which the whole galaxy rotates.

They've put the direction of the centre of the galaxy right in the middle of the image, and something instantly stands out - the movement of the earth (and sun) around the galaxy and how the rotation of the other stars in the galaxy isn't uniform.

Basically, the closer stars are to the centre of the Galaxy the faster they rotate, while the further out they are the slower.  There's a lot of nuance in that, but it'll do!

You can see that effect in the map.  Most of the right part of the map is red - the sun is rotating faster around the milky way than these stars are and so they are falling behind us, seeming to move backwards, but that isn't the case for all stars on the right most side of the map.  Stars closer into to the centre of the galaxy are rotating faster than us - they are catching us up, and you can see this group of stars as the blue centre of of the right side.  Stars on the same orbit as these stars on the left side of the map are in front of us are orbiting faster than us and so pulling away from us - hence the red centre on the left hand side of the map, while those further out orbit slower - we are catching them up, getting closer to them and hence they are coloured blue.

Beautiful.

 

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8 hours ago, Chinahand said:

ust like in a map of the globe you can put the centre of the map basically anywhere - for the globe it is only convention that has 0 degrees latitude through Greenwich and the same choice was faced by the astronomers in producing their map of the Milkyway's stars where to put the centre of their image.

Greenwich has been subject to astonishing, overnight, climate change according to local residents!

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There are a lot of stars in the Milky way.  How many?  Well zoom into this image and have a look.

It's an infrared image produced by the VISTA, the Visible and Infrared Survey Telescope for Astronomy, a 4.1 meter telescope with a 67 megapixel camera sensitive to infrared light located in the Chilean Atacama desert.

As it collects infrared light it sees through dust a lot easier than visible right, so the image is able to pick up many details not visible through standard telescopes; and my goodness are there a lot of stars visible.

Just think about each of those stars - many with planets - stretching for light year after light year. 

Wow!

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If you stare just off the end of the plough with a pair of binoculars or a small telescope you'll just catch a most slight smudge of light.  M51, the Whirlpool Galaxy - see the red dot at 13h30 and 45 degrees in the chart below.

M40_M97_M108_M109_Finder_Chart.jpg

 

If you were very patient with a larger telescope on a dark night you might see something like this:

3026073-m51_sketch_sw102_2009_small.jpg

NASA has larger resources and can stare for many hours with telescopes well above the atmosphere, and the result is something as stunning as this:

420970main_M51HST-GendlerMr_full.jpg

Stunning.  Look deeply into it - and the galaxies in the background.

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Typical Astronomy Stuff!

The Canada France Hawaii Telescope on Mauna Kea runs an image of the month observation time slot for when the weather isn't good enough for good science, so they slew the telescope and aim for something beautiful to photograph to add to the file.

You can find the archive here.

Sometime in 2017 the astronomers were planning their 2018 Calendar, and took this photo, which I think is quite wonderful!

Im1.jpg

It's deliberately highly saturated and exposed to deliberately bring out as much nebulosity and dust as possible.

Read more about it here.

I love the huge spiral galaxy (NGC 7331) at 11 o'clock just off centre, but the part of the image which really exited the astronomers is the cluster of galaxies towards the bottom and to the centre right - Stephan's Quintet.  The image revealed gas and stars ripped from the galaxies as they collide and interact (though one galaxy (NGC7320) at 40 million light years isn't actually a part of the actual galaxy group 300 million or so light years away).

4271_5.jpg

The result was that this pretty puff piece picture actually generated a lot of science (see here) and eventually a paper in the Monthly Notices of the Royal Astronomical Society and even more ironic it didn't even get into the calendar. Que sera sera.

Edited by Chinahand
Add another link!
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..............just mind boggling, too much for mere words...............thank you China...........

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I miss Carl Sagan. I'm currently re-watching the original Cosmos series.

 

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6 minutes ago, Snorri said:

I miss Carl Sagan. I'm currently re-watching the original Cosmos series.

 

You’ll be posting Noam Chomsky videos again soon 

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On 6/23/2018 at 2:08 PM, wrighty said:

In this month’s Manx Life magazine. Oh dear...

E61FC37C-076D-4400-9385-290D179C692F.jpeg

But typical of the editorial standards of that particular organ. It proclaims itself something like “The Island’s favourite for 30 years”. Favourite for hanging on a nail in the Thie Veg possibly. It makes IOM Newspapers look like Pulitzer candidates. I suspect the editor doesn’t know his Uranus from his elbow.

Edited by Uhtred

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