How We Solved the Mystery of Pulsating Auroras

Astronomers have finally observed what causes pulsating auroras, and our estimates of the mass of the Andromeda Galaxy have shrunk.

Hosted by: Hank Green
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[CyberiusT]

"Collision" for galaxies is more like clouds merging than the super-enormous car crash that word conjures up. There'll be gravitic mayhem and things thrown into intergalactic space (also a huge amount of new star formation), but not too much actual hitting.

[diegoreig]

At 5:26 I love his mix of enthusiastic and beeging tone

[seasong]

Already looking forward to the collision!

[LMacNeill]

3:06 “It’s hard to measure the mass of a whole galaxy, okay?!” I don’t know why, but that made me laugh...

[OlanKenny]

I'm not normally one to comment on other people's clothes
But Hank's jacket is REALLY NICE and it kinda makes him look like a professor/teacher

[minutesago]

Suggestion:
Episode on Escape Velocity
Planetary/solar/galactic
How is this calculated, relative to what, why variable, etc...
Thanks, love the channel

[NaginnahNibor]

Could you keep us up to date on any more news about the Andromeda Galaxy's mass?

[MusiCaninesTheMusicalDogs]

If our knowledge about the mass of Andromeda is that uncertain, I wonder how wrong we are about the mass of the whole universe! 😮

[tamastoth]

Hank is the best ".. precisely" xD

[chasesmith]

"..better pin down that mass." -Hank Green

[Ali]

PDA be like: "The Aurora suffered orbital hull failure. Cause: unknown. Zero human life signs detected."

[beardedroofer]

Electric Universe, Wallace Thornhill. Answers more questions than any other science and definitely needs more study.

[mr.rabbit]

That moment when you compare mass of the whole other galaxy to the mass of one star xD

Disc.: I know that Sun's mass is widely used in comparing masses of celestial bodies, but somehow using a fraction of X to determine X makes me smile.

[mexican.faerie]

So, could you say that somehow the pulsating auroras are related to Thomson cathode rays? I mean, it works with magnets as well, so could it be a relation on scale?

[krasnograd]

Gravitational colliding with Andromeda is already happening

[cybar]

What happened to Reid? He hasn't been on the last several videos.

[veyrenwolf]

Would it be possible to use similar principles to a railgun in terms of electromagnetic force being used to launch small probes into space without the need for super expensive chemical rockets?

[illusionz]

what happens if the star they used to trace the escape velocity was actually altered my coming into "gravitational contact" with a rogue black hole?

[aliensinnoh]

Aurora Borealis? At this time of the year? At this time of day? In this part of the country? Localized entirely within your kitchen?!

[manoj]

Here's an interesting idea,
Is it possible that there would exist a galaxy (far, far away of course) that the collective escape velocity would be greater than the speed of light?
So that they are not technically black-hole dense objects, but
a) the light does not escape from it
b) light struggles to get out and gets very heavily red shifted for our instruments
c) just gets deflected and curved to the point where it is not actually visible???
Now I'm curious, if they exist, how many of such objects are we missing, and would that constitute as some of the missing mass in our universe???