What If Earth Was Near the Center of the Milky Way?

WHAT IF

What's at the center of the Milky Way Galaxy and what would be different if Earth was positioned there?

Transcript

00:00 (music and explosion)

00:07 See that strip of stars

00:09 splashed across the night sky?

00:12 That's our home galaxy,

00:14 the Milky Way.

00:16 You can see it from Earth

00:17 because we live right on the outskirts,

00:19 far away from all the fun stuff

00:21 happening at its center.

00:23 What would it be like to reside

00:25 in its galactic downtown?

00:28 What would our night sky look like?

00:31 Would we get sucked into a black hole?

00:35 This is WHAT IF,

00:36 and here's what would happen

00:38 if the Earth was near the center

00:40 of the Milky Way.

00:41 (music and explosion)

00:43 The Milky Way is huge,

00:45 about 100,000 light-years across.

00:48 It has four large spiral arms

00:50 encircling its center.

00:52 That makes it a barred spiral galaxy,

00:55 just like most galaxies

00:57 in the observable Universe.

00:59 If the Earth packed up its belongings

01:01 and moved to the heart of the Milky Way,

01:04 things would be looking pretty bleak

01:05 for the survival of any kind of life

01:07 on the planet.

01:09 But not because of the Milky Way's

01:11 supermassive black hole.

01:13 (music and explosion)

01:16 The Earth is located in a quiet neighborhood

01:18 in one of the smallest spurs

01:19 of the Milky Way,

01:21 the Orion Arm.

01:23 We've got approximately 27,000 light-years

01:26 between us and the galactic center.

01:29 It's a comfortable spot to live in.

01:31 The temperatures on Earth

01:32 are just right to sustain life,

01:34 and there aren't too many space hazards

01:36 that could wipe out our existence.

01:38 (music and explosion)

01:42 Well, I didn't say it's completely safe,

01:44 did I?

01:46 Living anywhere near the center

01:47 of the Milky Way would be different.

01:50 It would depend on what part of that center

01:52 the Earth had the misfortune to occupy.

01:56 The closer you get to the heart of the galaxy,

01:58 the tighter the stars are packed together.

02:01 Because of this high star density,

02:03 the Earth would be blasted

02:04 with a lot more radiation

02:06 than what the Sun throws at you right now.

02:08 Under these circumstances,

02:10 the odds of life ever evolving

02:12 would be pretty small.

02:14 But if the Earth moved to the center,

02:16 together with all its inhabitants,

02:18 you'd find yourself very unlucky.

02:23 Earth's magnetosphere

02:24 wouldn't be able to protect you

02:25 from space radiation

02:26 blasting from all directions.

02:29 This could change the Earth's climate

02:31 and cause everything on the planet

02:32 to either mutate or die.

02:36 If you lived,

02:37 your biggest concern would be

02:38 a close encounter with a supernova.

02:41 A supernova occurs

02:42 when a massive star collapses,

02:44 releasing radio waves,

02:46 X-rays, cosmic rays,

02:47 and gamma rays into space.

02:51 For all we know,

02:52 one massive stellar body

02:54 could throw the Earth

02:55 out of the Sun's orbit.

02:56 Our planet would be surrounded

02:58 by foreign stars,

03:00 until one of them exploded in a supernova

03:02 and wiped us out for good.

03:04 But it would look spectacular from Earth,

03:06 if only for a brief moment.

03:09 There's another big hazard

03:11 that lies within the Milky Way's center,

03:13 a supermassive black hole

03:15 called Sagittarius A*.

03:18 If getting sucked into a black hole

03:20 isn't on your to-do list,

03:21 consider yourself lucky.

03:24 The Earth might stay far enough from it

03:26 that we wouldn't get engulfed

03:27 by this cosmic beast.

03:29 But we could get close enough

03:31 to get caught in the black hole's orbit.

03:34 At a distance of 20 billion km (1.2 billion mi)

03:37 from the black hole's event horizon,

03:39 the Earth could develop a speed

03:40 of 25 million km/h (1.2 billion mph).

03:44 That's over 230 times faster

03:46 than the speed our planet

03:47 is moving at right now.

03:50 So would that mean strong winds?

03:52 More natural disasters?

03:54 Would you end up flying off into space

03:56 and right into the black hole?

03:59 It sure wouldn't be good for you,

04:00 or anything else on the Earth's surface.

04:03 The Earth is perfectly designed

04:05 to be right where it is.

04:07 It can survive on the outskirts of the galaxy,

04:10 but you wouldn't want it to be anywhere else.

04:13 The most dangerous place

04:14 for a planet to be located

04:16 is anywhere near the center of a galaxy,

04:18 any galaxy.

04:20 If you just want a nice view,

04:22 your best bet might be to teleport the Earth

04:25 to the middle of a nebula instead.

04:28 But that's a story for another WHAT IF.

04:32 ♪ ♪

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