1. NASA Educator Ambassador
Title Page
Janet Moore
NASA Educator Ambassador

2. Definition: a place where the escape velocity is faster
What is a Black Hole? ?
Definition: a place where the
escape velocity is faster
than the speed of light.

3. Close-up Picture of a Black Hole

4. Definition: the velocity at which something must travel
Escape Velocity ?
Definition: the velocity at
which something must travel
away from an object
such that the gravity
of the object
cannot stop it.

5. Escape Velocity (2) Escape velocity depends on the gravity
of the object

6. Escape Velocity (3) ^ Low mass Medium mass High mass Very high mass
for a given radius ^
Low
mass
Medium
mass
High
mass
Very
high
mass

7. Escape Velocity (4)
radius decreases
increases

8. It’s an object of high enough mass and small enough radius
What is a Black Hole?
It’s an object of high enough mass
and small enough radius
such that
the escape velocity is
faster than light.
Nothing can escape.

9. Or, put another way …

10. The First Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in

11. Down the Drain

12. Black holes are really massive,
Forcing the Issue
The force of gravity from an object depends on
1) the mass of the object
2) your distance from it
Gm1m2 F= r2
So if it’s really massive, or you’re really close, the force is high.
Black holes are really massive,
And you can get
really, really close
But this means….

13. Forcing the Issue (2) The force you feel CHANGES as you get closer.
Something closer to the black hole feels MORE force.
STRETTTTTCH!
If you fall in feet first, you have a problem.

14. There is a Tide BLACK HOLE TIDES The change in force is called a TIDE
Tides on surface of Earth (distance = 6400 km)
: 1/1,000,000th of a g
(for a 3 solar mass black hole)
6400 km
Fup
Fdown
DISTANCE
FORCE (g)
6400 km
0.5
2000 18
1000
144
100
150,000 10
150,000,000
BLACK HOLE TIDES

15. The Second Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification

16. Why the long face?

17. The Third Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it’s born

18. Cold War, Hot Topic NOT ONE WAS OF THIS EARTH
Vela Satellites flown to detect
nuclear explosions on Earth
in 1960s and 1970s
by looking for gamma rays
Over their lifetime, they detected 73 events.
NOT ONE WAS OF THIS EARTH

19. Gamma Ray Bursts
GRBs happen every day,
somewhere in the Universe

20. The Birth of a Black Hole
Hypernova!
Coalescing
neutron stars

21. over its entire lifetime.
Birth Pangs
Energy generated in a GRB = 1052 ergs
This is 10x the
Sun’s total energy
over its entire lifetime.
Enough energy to vaporize the Earth
100 billion times over.

22. Pfffssssst!

23. NASA’s Swift Response Swift detects >100 GRBs per year Launched
November 20, 2004

24. The Fourth Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it dies

25. Black holes radiate away energy
Pare Production
Particles created here
Free at last!
Buh bye!
Hawking Radiation:
2 particles created,
one particle leaves
Black hole
Net Effect:
Black holes radiate away energy

26. radiation faster as size shrinks.
Size Does Matter
Hawking radiation depends on size/mass of the black hole:
smaller holes radiate faster!
In fact, radiation emitted goes as 1/mass3
Stellar black hole lives for 1067 years
A mini black hole
(mass =1012 kg)
would be exploding now
Emits higher energy
radiation faster as size shrinks.
KABOOM!

27. The Fifth Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it dies
Just passing through

28. not It’s a Wonderful Day in the Neighborhood

29. What if . . .
What would happen
if the sun became a
black hole?

30. Solar System Black Hole

31. The Sixth Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it dies
Just passing through
Be nearby when they merge

32. When Galaxies Collide

33. expand and contract space itself
Wave Bye Bye
Gravitational waves
expand and contract space itself

34. The Long and the Short of It

35. ESA’s Response: LISA 3 “Wagon wheels” That will detect passing
gravitational
waves
Target launch: 2014

36. The Seventh Way A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it dies
Just passing through
Be nearby when they merge
Fried by the light

37. Traveling Companion HD 226868: just your typical
bloated supergiant star…
but it has a secret
Cygnus X-1
HD in X-rays
(100,000x energy of Sun!)
Hey, where is it?

38. The Hideous Vortex

39. Disks and Fields and Jets, Oh My

40. Not-so-compact Disk

41. Angry Neighbors M 87 Cygnus A (60 million light years)

42. Our GLAST (Fermi) Resort
Gamma-Ray
Large Area
Space Telescope
Launched:
June 2008
Fermi will see
thousands of
active galaxies

43. The Seven Ways A Black Hole Can Kill You1. 2. 3. 4. 5. 6. 7.
Falling in
Spaghettification
Be near one when it’s born
Be near one when it dies
Just passing through
Be nearby when they merge
Fried by the light

44. What’s on the other side…?

45. Questions?

46. The Sky by Eye

47. DIRBE’s Milky Way

48. EXTREME Close up

49. The Monster in the Middle

50. Video Disk