1
00:00:01,000 --> 00:00:03,500
There’s so many discoveries that Hubble has made. 

2
00:00:03,700 --> 00:00:08,500
Some that we knew we would make such as measuring the speed of the expansion of the Universe,

3
00:00:08,700 --> 00:00:13,700
verifying the existence of black holes, and then there’s some that were completely unexpected.

4
00:00:13,700 --> 00:00:18,300
In fact, my favourite I think is one that when Hubble was launched, 

5
00:00:18,500 --> 00:00:21,500
we didn’t know about any extrasolar planets.

6
00:00:21,500 --> 00:00:24,500
So my favourite Hubble discovery if you will,

7
00:00:24,500 --> 00:00:29,700
 is the measurement of the atmosphere of a planet around a nearby star, 

8
00:00:30,000 --> 00:00:32,000
that was made by the STIS instrument.

9
00:00:32,300 --> 00:00:38,500
I think it really boggles the mind, or stimulates the imagination

10
00:00:38,700 --> 00:00:42,700
to think that here on Earth with a telescope in orbit, 

11
00:00:43,000 --> 00:00:47,000
we can actually spy on other planets in other solar systems.

12
00:01:02,000 --> 00:01:05,000
Hubblecast Episode 42: Hubble’s greatest hits

13
00:01:08,000 --> 00:01:13,000
Presented by Dr J, aka Dr Joe Liske

14
00:01:16,000 --> 00:01:18,000
Hello and welcome to the Hubblecast. 

15
00:01:18,300 --> 00:01:23,000
How do we know if a scientific discovery is really important, or somehow special?

16
00:01:24,000 --> 00:01:29,000
Well, when astronomers obtain a result, they usually write it up in an article for a scientific journal. 

17
00:01:29,300 --> 00:01:33,500
And one way to know whether the result is important or not is to look at 

18
00:01:33,700 --> 00:01:37,500
how often other astronomers refer to this article in their work.

19
00:01:38,000 --> 00:01:42,000
That’s the simple answer anyway. But there’s a human component too. 

20
00:01:42,300 --> 00:01:46,000
Some discoveries simply capture our imagination more than others, 

21
00:01:46,300 --> 00:01:50,700
and that too is an important part of what makes a truly great discovery.

22
00:01:51,700 --> 00:01:56,500
In this episode, we’re going to talk to some leading astronomers who use the Hubble Space Telescope, 

23
00:01:56,800 --> 00:02:00,000
and we’re going to ask them about their favourite Hubble moments.

24
00:02:01,500 --> 00:02:07,000
My favourite Hubble discovery is of course one of my own! 

25
00:02:07,300 --> 00:02:11,500
It was a surprise that should not have been a surprise. 

26
00:02:11,700 --> 00:02:20,000
When we first looked at the Orion nebula, this region of nearby star formation, 

27
00:02:20,300 --> 00:02:27,500
we found that we could actually see protoplanetary discs around many of the stars. 

28
00:02:27,700 --> 00:02:33,500
Now, we should have expected to see this, we should have been looking for it, 

29
00:02:33,700 --> 00:02:36,500
but we were looking for something else and found that.

30
00:02:38,500 --> 00:02:43,500
It was a wonderful feeling, to discover the protoplanetary disc. 

31
00:02:43,700 --> 00:02:51,000
It was the closest thing to a ‘eureka’ moment that I have ever had in science. 

32
00:02:51,300 --> 00:02:59,700
You look at the image and then suddenly everything comes together. You know exactly what you’ve seen.

33
00:03:00,000 --> 00:03:06,000
And you’re seeing something that no-one else had ever seen before. It was wonderful.

34
00:03:08,500 --> 00:03:13,500
I’ve done a lot of research with Hubble and in fact almost all my work has been done with or based on Hubble images. 

35
00:03:13,700 --> 00:03:20,700
But perhaps my very favourite was this one galaxy that we observed very very early on. NGC 4261.

36
00:03:20,700 --> 00:03:28,500
And what we saw when we looked at this galaxy was that there is a very small disc of gas and dust at the centre 

37
00:03:28,500 --> 00:03:34,000
and we could use the velocity of the gas in the disc to measure the mass of the central supermassive black hole.

38
00:03:34,000 --> 00:03:38,500
And that was one of the very first conclusive evidence for the presence of a black hole in a galaxy.

39
00:03:39,500 --> 00:03:44,000
I think that my favourite Hubble discovery is based on aesthetics. 

40
00:03:44,300 --> 00:03:52,700
And it’s the imaging of these giant clusters of galaxies that show these beautiful gravitational lenses. 

41
00:03:52,700 --> 00:03:55,700
The red cluster galaxies and the blue background galaxies.

42
00:03:58,000 --> 00:04:03,500
General relativity in action there, bending light and making images that are just stunning. 

43
00:04:04,700 --> 00:04:06,300
I wish I had done that!

44
00:04:07,700 --> 00:04:11,700
Actually, early on we weren’t even certain that Hubble was going to be able to see distant galaxies. 

45
00:04:12,000 --> 00:04:18,500
When Hubble was first being designed the thought was that as you farther and farther back in time,

46
00:04:18,700 --> 00:04:25,500
farther and farther out in the Universe, galaxies would become just fainter, low surface brightness, 

47
00:04:25,700 --> 00:04:30,500
just sort of faint, diffuse blobs, and you wouldn’t be able to see them very well with Hubble. 

48
00:04:31,500 --> 00:04:38,500
In fact, galaxies aren’t just faint, diffuse blobs, they have a lot of structure, and a lot of regions within them

49
00:04:38,700 --> 00:04:42,700
that are bright because of stars being born right there.

50
00:04:43,000 --> 00:04:49,700
And so it has been not only possible with Hubble to directly detect very distant galaxies, 

51
00:04:50,000 --> 00:04:57,500
but now we’ve actually seen objects that emitted their light when the Universe was only 700 or 800 million years old.

52
00:04:57,700 --> 00:05:01,700
And of course the Universe today is 13.7 billion years old. 

53
00:05:02,000 --> 00:05:06,000
So we’re looking back in the early nursery of our Universe, 

54
00:05:06,300 --> 00:05:11,700
and seeing the toddler galaxies as they’re just coming along and starting to grow.

55
00:05:20,500 --> 00:05:29,000
I tend to favour the wonderful images that have allowed to obtain very tight and deep colour-magnitude diagrams, 

56
00:05:29,300 --> 00:05:34,500
see how stars form and evolve in nearby galaxies.

57
00:05:40,500 --> 00:05:45,300
I think that the beautiful pictures of the dust clouds that are on everyone’s desk 

58
00:05:45,300 --> 00:05:48,300
are so amazingly beautiful that they say well can we have some more?

59
00:05:48,500 --> 00:05:55,700
And so as a scientist I look at that cloud and say that cloud’s beautiful but is hiding what I know about. 

60
00:05:56,000 --> 00:06:01,500
So inside that cloud are stars that have been born recently or stars maybe about to be born. 

61
00:06:01,700 --> 00:06:05,700
And it tells us right away that we need to use infrared to see inside those clouds. 

62
00:06:05,700 --> 00:06:10,700
So that’s the sort of the thing that I think about the most from the Hubble.

63
00:06:16,000 --> 00:06:23,500
I did some work on a fantastic young star forming region called NGC 346,  which has beautiful images of it.

64
00:06:23,700 --> 00:06:33,700
And being able to look at how young stars are born and how they influence their molecular clouds around them, 

65
00:06:34,000 --> 00:06:39,300
and just to see the fantastic structure in the H II regions, is great, I mean I can,

66
00:06:39,500 --> 00:06:42,300
I just spend so much time looking at these images and I never tire of them,

67
00:06:42,500 --> 00:06:46,500
because you always learn something every time you look at them.

68
00:06:48,000 --> 00:06:52,500
So clearly Hubble has made a lot of fantastic observations of the Universe during its lifetime. 

69
00:06:52,700 --> 00:06:57,300
And I for one find it really hard to pick what my favourite Hubble moment is.

70
00:07:01,500 --> 00:07:07,300
So one of my favourite Hubble achievements were the images Hubble took of planet Fomalhaut b. 

71
00:07:07,500 --> 00:07:11,800
These were the first images of an extrasolar planet that were taken in optical light.

72
00:07:12,000 --> 00:07:19,700
And by using multiple observations, Hubble allowed us to watch this planet move on its orbit around its parent star.

73
00:07:22,500 --> 00:07:27,500
So another great Hubble moment were the images that it took of the so-called Bullet Cluster. 

74
00:07:27,800 --> 00:07:32,700
These are actually two colliding clusters of galaxies that demonstrate beautifully the existence of dark matter.

75
00:07:34,500 --> 00:07:38,000
And then of course the Hubble Space Telescope measured the so-called Hubble constant,  

76
00:07:38,300 --> 00:07:40,700
which is the expansion speed of the Universe.

77
00:07:41,000 --> 00:07:43,700
Hubble did this more precisely than was ever done before –

78
00:07:44,000 --> 00:07:48,500
and of course this was one of the main reasons why Hubble was built in the first place.

79
00:07:49,500 --> 00:07:56,500
This is Dr J signing off for the Hubblecast. Once again, nature has surprised us beyond our wildest imagination.

80
00:07:59,500 --> 00:08:02,500
Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany.

81
00:08:02,700 --> 00:08:05,500
The Hubble mission is a project of international cooperation between NASA and European Space Agency.

82
00:08:08,000 --> 00:08:10,500
 Transcribed by ESA/Hubble