# Supernova bubble clocked at 19,000,000 km/h

Astronomers have produced a fetching animation of the inexorable outwards expansion of the remains of the Tycho Type Ia supernova - a white dwarf in a binary star system which went bang in spectacular fashion back in 1572. The explosion was so bright it was visible from Earth during the day, even at a distance of some 10,000 …

1. #### My God,

it's full of stars!

1. #### Re: My God,

TBH, it looks more to me like it's full of trees.

1. #### Re: My God,

Integral Trees?

2. #### A long time ago and far, far away...

The phrases "went bang in spectacular fashion back in 1572." and "at a distance of some 10,000 light years" should not be used together. Not for a long while anyway.

1. #### Re: A long time ago and far, far away...

It appeared bang in spectacular fashion back in 1572

2. #### Re: A long time ago and far, far away...

It's all relative.

3. #### Re: A long time ago and far, far away...

At a distance of 10K light years, that would mean that the explosion happened in 8428 BC

Right around the time man was domesticating dogs, learning to herd sheep and make boats.

Yes Virginia, the Universe is really a big place.

3. #### "supersonic" expansion?

What exactly is the speed of sound in a vacuum these days?

1. #### Re: "Supersonic"?

Space isn't a perfect vacuum, so you can still sensibly talk about the speed of sound. It depends on the local density (which varies considerably), but order of magnitude should be ~100 km/sec or 360,000 km/h.

Incidentally 19,000,000 km/h is getting on for 0.02c.

1. #### Re: "Supersonic"?

I would posit (ie. guess) that anything moving fast enough to create a compression layer ahead of it is supersonic.

2. #### Re: "Supersonic"?

"Incidentally 19,000,000 km/h is getting on for 0.02c."

This. I don't want to know astronomical speeds in km/h, let alone mph. km/s please, which is easy to relate to c at around 300 000km/s.

It's roughly 5300 km/s which is easier to get your head around.

4. #### 19,000,000 km/h ?

With that kind of magnitude, shouldn't we say it's moving at over 5000 km/s instead?

Sure sounds more impressive to me!

1. #### Re: 19,000,000 km/h ?

Let's face it, that's bloody fast, however you quantify it.

1. #### Re: 19,000,000 km/h ?

Come on Lester, surely you should have replied with;

176.0433% of the maximum velocity of a sheep in a vacuum.

or

45600000000000 linguine per fortnight

or

32975343.55464 brontosaurus per ke

Come on man. It's your job to enforce standard units at your worklpace.

1. #### Re: Re: 19,000,000 km/h ?

Looks like you've already done the job for me. Good show.

2. #### Re: 19,000,000 km/h ?

Yes, but how fast was Han Solo when he made the Kessel Run in 12 parsecs?

1. #### Re: 19,000,000 km/h ?

"Yes, but how fast was Han Solo when he made the Kessel Run in 12 parsecs?"

AFAIK a parsec is a measure of distance !

1. #### Re: 19,000,000 km/h ?

"AFAIK a parsec is a measure of distance !"

See icon!

2. #### Re: 19,000,000 km/h ?

""Yes, but how fast was Han Solo when he made the Kessel Run in 12 parsecs?""

Though I know this was a straight up scientific error in the film, it could actually be possible as an explanation. Suppose in a world of hyperluminal travel there is a star between you and the destination, which is 11 parsecs away. Your path of least action is also the longest path. The more energy you have available the closer you can pass to the star, and the shorter your path will be. Since you're moving in 4-dimensional spacetime, you can express the path equally in terms of time and distance since the one will determine the other. Since time is relative to the observer Han Solo would state the distance in parsecs, because his perceived time for the trip would be different from that of an observer, whereas once parked on the destination both he and the observer would agree fairly closely on the path length.

I think there is something similar with sailing ships. The closer a ship can sail to the wind, the shorter the path it can take, say, across the Atlantic. A tea clipper would not only be faster than HMS Victory on that route, it would potentially need a shorter distance because it could sail more northerly.

1. #### Re: 19,000,000 km/h ?

"Though I know this was a straight up scientific error in the film,"

What film ?

1. #### Re: 19,000,000 km/h ?

The Historical Documents.

3. #### Re: 19,000,000 km/h ?

AFAIK a parsec is a measure of distance !

Correct, and Han Solo made the run in a record short distance: 12 parsecs. Other pilots took longer routes to complete the Kessel Run.

3. #### Re: 19,000,000 km/h ?

I like to measure thing in Angstroms per century. Just to get a good feel for the magnitude.

PS I also like writing down zeros. So it's about 1.66x10^25 or 16600000000000000000000000.

5. 19,000,000 km/h = 176.0433 % of the maximum velocity of a sheep in a vacuum.

Yep, that's pretty fast.

warp and weft drive in fact

6. Has it been expanding at that rate the entire 444 years? If so, my sloppy calculations say it should be around 1,086,379,368,040,875.4 brontosauri across. That'd be over 93 trillion miles here in 'Murca, and just under 16 light-years (although that seems wrong but, eh, I did say it's "sloppy")

1. Well it certainly can't speed up, so if it is expanding at 0.0176c now then your sloppy calculation should be roughly correct for the diameter of the wave front.

7. #### Why indeed the observable Universe may not be spherical...

"Although the remnant is approximately circular, there are clear differences in the speed of the blast wave in different regions. The speed in the right and lower right directions is about twice as large as that in the left and the upper left directions."

I think the Universe is cat shaped

1. #### Re: Why indeed the observable Universe may not be spherical...

Artist's renderings of what our galaxy would look like from afar bear a striking resemblance to a sphincter. That would explain a lot about our world.

1. #### Re: Why indeed the observable Universe may not be spherical...

Would also explain Klingons!

1. #### Re: Why indeed the observable Universe may not be spherical...

...and of course the Captain's log.

2. #### Re: Why indeed the observable Universe may not be spherical...

"I think the Universe is cat shaped"

It's turtles, all the way down.

3. #### Re: Why indeed the observable Universe may not be spherical...

I think the Universe is cat shaped

Whatever it is, it's not at all shaped like a spherical cow of uniform density.

8. #### Consensus?

Is there scientific consensus for any of the statistics or results mentioned in this article? Seems like a bunch of the information comes from NASA who have been promoting things like climate change. How can we believe any of this guff?

9. Isn't that the thing that threatens to destroy the ship, but turns out to be the toy of a galactic super-being toddler?

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