WEBVTT

0
00:00:00.000 --> 00:00:02.880
Anna: Welcome to Astronomy Daily, your daily dose

1
00:00:02.880 --> 00:00:05.840
of space and astronomy news. I'm Anna.

2
00:00:06.000 --> 00:00:08.920
Avery: And I'm, um, avery. It's Thursday, the 16th

3
00:00:08.920 --> 00:00:11.840
of July, 2026, and we have a

4
00:00:11.840 --> 00:00:14.160
genuinely lovely lineup for you today,

5
00:00:14.480 --> 00:00:17.000
including a story that's been 10 years in the

6
00:00:17.000 --> 00:00:19.960
making, or more accurately, 10 years in the

7
00:00:19.960 --> 00:00:20.400
hiding.

8
00:00:20.800 --> 00:00:23.400
Anna: That's Our lead astronomers have finally

9
00:00:23.400 --> 00:00:25.560
caught a planet that's been playing hide and

10
00:00:25.560 --> 00:00:28.220
seek with them for over a decade. And it

11
00:00:28.220 --> 00:00:31.020
turns out to be the faintest exoplanet ever

12
00:00:31.020 --> 00:00:33.860
imaged from Earth. And it lives in a southern

13
00:00:33.860 --> 00:00:36.340
constellation, which makes it feel just a

14
00:00:36.340 --> 00:00:37.420
little bit like ours.

15
00:00:37.660 --> 00:00:40.220
Avery: We've also got the completion of a nine year

16
00:00:40.220 --> 00:00:42.900
project to build the sharpest radio map of

17
00:00:42.900 --> 00:00:45.900
the entire sky. And the James Webb Space

18
00:00:45.900 --> 00:00:48.660
Telescope catching a supermassive black hole

19
00:00:48.660 --> 00:00:50.540
in the act of feeding itself.

20
00:00:50.940 --> 00:00:53.380
Anna: Then it's a double bill from the outer solar

21
00:00:53.380 --> 00:00:56.200
system. Landslides on Pluto spotted for

22
00:00:56.200 --> 00:00:59.080
the first time, and evidence that Pluto's big

23
00:00:59.080 --> 00:01:01.760
moon, Charon, once spun more than 10

24
00:01:01.760 --> 00:01:03.760
times faster than it does today.

25
00:01:04.240 --> 00:01:06.680
Avery: And we'll wrap the news with some sobering

26
00:01:06.680 --> 00:01:09.680
numbers. SpaceX's Starlink satellites had

27
00:01:09.680 --> 00:01:11.840
to dodge potential collisions more than

28
00:01:11.840 --> 00:01:14.680
355,000 times

29
00:01:14.680 --> 00:01:17.240
in the past year. We'll unpack what that

30
00:01:17.240 --> 00:01:18.440
means for everyone's

31
00:01:18.440 --> 00:01:21.320
Anna: orbit, plus your Southern hemisphere sky

32
00:01:21.320 --> 00:01:23.430
watching for tonight. Let's get into it.

33
00:01:23.590 --> 00:01:25.150
Avery, cast your mind.

34
00:01:25.150 --> 00:01:27.870
Back in 2008, astronomers

35
00:01:27.870 --> 00:01:30.230
directly imaged a planet around the young

36
00:01:30.310 --> 00:01:33.310
star Beta Pictoris, one of the very first

37
00:01:33.310 --> 00:01:36.150
exoplanets ever photographed. That was

38
00:01:36.150 --> 00:01:38.950
Beta Pictoris B. A second planet

39
00:01:38.950 --> 00:01:41.770
C followed. And ever since, there's been a,

40
00:01:41.770 --> 00:01:44.150
uh, nagging suspicion that the system was

41
00:01:44.150 --> 00:01:44.630
hiding

42
00:01:44.630 --> 00:01:46.870
Avery: something more because of the disk. Right.

43
00:01:47.030 --> 00:01:49.410
Beta Pictoris has this magnificent debris,

44
00:01:49.410 --> 00:01:51.870
uh, disk. It's the poster child for planet

45
00:01:51.870 --> 00:01:54.350
formation. And parts of it were warped and

46
00:01:54.350 --> 00:01:56.510
sculpted in ways that two known planets

47
00:01:56.510 --> 00:01:57.870
couldn't fully explain.

48
00:01:58.270 --> 00:02:01.030
Anna: Exactly. And now we know why. In a

49
00:02:01.030 --> 00:02:02.710
study published Wednesday in the

50
00:02:02.710 --> 00:02:05.510
Astrophysical Journal Letters, a team using

51
00:02:05.510 --> 00:02:08.070
the European Southern Observatory's Very

52
00:02:08.070 --> 00:02:11.030
Large Telescope in Chile has confirmed a

53
00:02:11.030 --> 00:02:13.630
third planet, Beta Pictoris D.

54
00:02:13.950 --> 00:02:16.430
And here's the headline. It's roughly

55
00:02:16.590 --> 00:02:19.470
100 times fainter than Beta Pictoris

56
00:02:19.470 --> 00:02:22.390
B, which makes it the faintest exoplanet

57
00:02:22.390 --> 00:02:24.430
ever directly imaged from Earth.

58
00:02:25.130 --> 00:02:27.650
Avery: A hundred times fainter. To put that in

59
00:02:27.650 --> 00:02:30.010
context for everyone, direct imaging means

60
00:02:30.010 --> 00:02:32.490
actually capturing the planet's own light in

61
00:02:32.490 --> 00:02:34.810
a photograph next to a star that's

62
00:02:34.810 --> 00:02:37.490
overwhelmingly brighter. It's often compared

63
00:02:37.490 --> 00:02:40.410
to spotting a firefly next to a lighthouse.

64
00:02:40.890 --> 00:02:43.210
This is spotting a very Dim

65
00:02:43.210 --> 00:02:43.930
firefly.

66
00:02:44.330 --> 00:02:47.210
Anna: And the discovery itself was serendipitous.

67
00:02:47.370 --> 00:02:50.210
Ben Sutliff at the University of Edinburgh

68
00:02:50.210 --> 00:02:52.490
who co led the study, said they were

69
00:02:52.490 --> 00:02:55.050
originally just going back to study the known

70
00:02:55.050 --> 00:02:57.780
planet Beta Pictoris B to see how it

71
00:02:57.780 --> 00:03:00.300
changed over time. But in their new images

72
00:03:00.300 --> 00:03:03.300
from the VLT's Eris instrument, there was

73
00:03:03.300 --> 00:03:05.580
something else. A faint point of light

74
00:03:05.580 --> 00:03:08.500
separated from Planet B that sent them down

75
00:03:08.500 --> 00:03:10.220
an entirely new path.

76
00:03:10.540 --> 00:03:12.940
Avery: And this is where the hide and seek comes in.

77
00:03:13.100 --> 00:03:15.420
Once they knew what to look for, they trawled

78
00:03:15.420 --> 00:03:17.660
back through the archives. And there it was,

79
00:03:17.980 --> 00:03:20.100
lurking. In more than a decade of old

80
00:03:20.100 --> 00:03:22.700
observations from the VLT SPEAR instrument

81
00:03:23.030 --> 00:03:25.510
and even in James Webb Space Telescope data,

82
00:03:25.750 --> 00:03:28.390
the planet had been photographed for years.

83
00:03:28.870 --> 00:03:30.150
Nobody had noticed.

84
00:03:30.550 --> 00:03:33.430
Anna: Co author Jane Burkeby at Oxford put it

85
00:03:33.430 --> 00:03:36.110
beautifully. Planet D has been playing hide

86
00:03:36.110 --> 00:03:38.870
and seek with us for over a decade and now

87
00:03:38.870 --> 00:03:40.390
we can say found you.

88
00:03:40.790 --> 00:03:42.870
Avery: So what do we know about the world itself?

89
00:03:43.270 --> 00:03:46.110
Anna: It's a gas giant about 2.4 times

90
00:03:46.110 --> 00:03:48.830
the mass of Jupiter, which sounds big, but

91
00:03:48.830 --> 00:03:50.870
is actually the lightweight of the family.

92
00:03:51.400 --> 00:03:54.160
Planets B and c are each 10 Jupiter

93
00:03:54.160 --> 00:03:57.080
masses. Planet D sits, um, much further out

94
00:03:57.080 --> 00:03:59.800
from the star on a wide orbit, so it's cooler

95
00:03:59.800 --> 00:04:02.000
and dimmer than its siblings, hence the

96
00:04:02.000 --> 00:04:04.560
difficulty. And satisfyingly, its

97
00:04:04.560 --> 00:04:07.159
presence helps explain that odd structure in

98
00:04:07.159 --> 00:04:09.560
the debris disk that's puzzled astronomers

99
00:04:09.560 --> 00:04:10.120
for years.

100
00:04:10.600 --> 00:04:13.240
Avery: There's also a nice milestone tucked in here.

101
00:04:13.480 --> 00:04:15.880
This makes Beta Pictoris only the second

102
00:04:15.960 --> 00:04:18.200
planetary system after HR

103
00:04:18.200 --> 00:04:20.840
8799, where more than two

104
00:04:20.840 --> 00:04:23.720
planets have been directly. We're building

105
00:04:23.720 --> 00:04:26.280
up actual family portraits of other solar

106
00:04:26.280 --> 00:04:26.960
systems now.

107
00:04:27.280 --> 00:04:29.840
Anna: And an independent team at the University of

108
00:04:29.840 --> 00:04:32.280
California spotted the same object in their

109
00:04:32.280 --> 00:04:34.920
own data at almost the same time, which gives

110
00:04:34.920 --> 00:04:37.720
the detection real confidence. Now the

111
00:04:37.720 --> 00:04:40.680
bit our audience will love. Beta Pictoris is

112
00:04:40.680 --> 00:04:43.240
a southern star. It sits in the constellation

113
00:04:43.240 --> 00:04:46.160
Pictor, the Painter's Easel, just next to

114
00:04:46.160 --> 00:04:48.960
brilliant canopus. And at 63 light

115
00:04:48.960 --> 00:04:51.280
years away, it's visible from Australia and

116
00:04:51.280 --> 00:04:53.750
New Zealand. Though right now in July

117
00:04:53.990 --> 00:04:56.790
it's low in our evening sky and best hunted

118
00:04:56.790 --> 00:04:58.310
in the pre dawn hours later in

119
00:04:58.310 --> 00:05:01.030
Avery: the year, a planetary system with three

120
00:05:01.030 --> 00:05:03.510
photographed worlds sitting in our southern

121
00:05:03.510 --> 00:05:05.190
sky. Not bad at all.

122
00:05:05.510 --> 00:05:08.510
Next, A, uh, project nine years in the

123
00:05:08.510 --> 00:05:11.510
making has just crossed the finish line. The

124
00:05:11.510 --> 00:05:14.070
U.S. national Science Foundation's National

125
00:05:14.230 --> 00:05:17.190
Radio Astronomy Observatory has announced

126
00:05:17.270 --> 00:05:20.230
that observations for the Very Large Array

127
00:05:20.230 --> 00:05:22.660
Sky Survey VLAS are

128
00:05:22.660 --> 00:05:25.660
complete. It's the most detailed radio

129
00:05:25.660 --> 00:05:27.980
survey of the sky ever conducted.

130
00:05:28.620 --> 00:05:31.220
Anna: This is the VLA in New Mexico. The

131
00:05:31.220 --> 00:05:34.100
iconic Y shaped array of 27 dishes

132
00:05:34.100 --> 00:05:36.540
from every space documentary ever made.

133
00:05:36.860 --> 00:05:39.660
Avery: That's the one. From September 2017

134
00:05:39.980 --> 00:05:42.500
through February this year, the array

135
00:05:42.500 --> 00:05:45.180
repeatedly swept about 34,000

136
00:05:45.340 --> 00:05:48.340
square degrees. Essentially the whole sky

137
00:05:48.340 --> 00:05:51.010
visible from New Mexico and everything north

138
00:05:51.010 --> 00:05:53.290
of minus 40 degrees declination.

139
00:05:53.690 --> 00:05:56.490
That's roughly 80% of the entire

140
00:05:56.490 --> 00:05:59.290
celestial sphere. Mapped at a resolution

141
00:05:59.290 --> 00:06:02.050
of about 2 and a half arcseconds in the 2

142
00:06:02.050 --> 00:06:03.610
to 4 GHz band.

143
00:06:03.850 --> 00:06:05.690
Anna: And how does that compare to what came

144
00:06:05.690 --> 00:06:06.010
before?

145
00:06:06.490 --> 00:06:09.170
Avery: It's about 18 times sharper than the

146
00:06:09.170 --> 00:06:12.010
previous benchmark all sky radio survey from

147
00:06:12.010 --> 00:06:14.250
the 1990s. The numbers are

148
00:06:14.330 --> 00:06:16.940
staggering. Roughly six and a half thousand

149
00:06:17.170 --> 00:06:20.170
thousand observing hours. Half a petabyte of

150
00:06:20.170 --> 00:06:22.890
raw data. And the processed data products are

151
00:06:22.890 --> 00:06:25.570
expected to reach around 2 petabytes, the

152
00:06:25.570 --> 00:06:28.330
largest data volume the VLA has ever

153
00:06:28.330 --> 00:06:31.250
produced. They use a clever on the fly

154
00:06:31.250 --> 00:06:34.090
mosaicing technique where the antennas sweep

155
00:06:34.090 --> 00:06:36.810
continuously across the sky in a raster

156
00:06:36.810 --> 00:06:39.170
pattern rather than stopping to point at each

157
00:06:39.170 --> 00:06:39.490
field.

158
00:06:39.890 --> 00:06:42.850
Anna: And crucially, they surveyed the sky multiple

159
00:06:42.850 --> 00:06:45.730
times over those nine years. Which means VLAS

160
00:06:45.730 --> 00:06:48.590
isn't just a map, it's a movie. Comparing

161
00:06:48.590 --> 00:06:51.150
epochs revealed a dynamic radio sky.

162
00:06:51.230 --> 00:06:53.830
Sources that flare, fade or appear from

163
00:06:53.830 --> 00:06:56.630
nowhere. Exploding stars, feeding black

164
00:06:56.630 --> 00:06:58.910
holes, colliding neutron stars.

165
00:06:59.310 --> 00:07:01.870
Avery: Which brings us to the timing. And honestly,

166
00:07:01.870 --> 00:07:03.950
the timing is the best part of the story.

167
00:07:04.510 --> 00:07:07.430
Just over two weeks ago on June 30, the

168
00:07:07.430 --> 00:07:10.350
Vera C. Rubin Observatory in Chile began

169
00:07:10.350 --> 00:07:13.150
its decade long legacy survey of space and

170
00:07:13.150 --> 00:07:15.930
time, sweeping the southern optical sky

171
00:07:16.010 --> 00:07:18.890
every few nights. So for the first time in

172
00:07:18.890 --> 00:07:21.690
history, we have a complete high resolution

173
00:07:21.770 --> 00:07:24.450
radio map and a real time optical

174
00:07:24.450 --> 00:07:27.130
transient stream operating simultaneously.

175
00:07:27.450 --> 00:07:29.889
Anna: Though when Rubin flags something going bang

176
00:07:29.889 --> 00:07:32.330
in the optical, astronomers can immediately

177
00:07:32.330 --> 00:07:34.690
check what that patch of sky looks like and

178
00:07:34.690 --> 00:07:37.690
looked like in the radio. The whole multi

179
00:07:37.690 --> 00:07:39.690
wavelength discovery machine the community

180
00:07:39.690 --> 00:07:42.250
has spent two decades building is now

181
00:07:42.250 --> 00:07:44.510
switched on and the data's public.

182
00:07:44.750 --> 00:07:47.470
Avery: Radio astronomers, multi wavelength folks,

183
00:07:47.710 --> 00:07:50.670
citizen scientists. The radio sky now

184
00:07:50.670 --> 00:07:52.110
belongs to everyone.

185
00:07:52.670 --> 00:07:55.310
Anna: Now to a decades old mystery that may

186
00:07:55.310 --> 00:07:57.910
finally have its answer. Avery, how do

187
00:07:57.910 --> 00:08:00.270
supermassive black holes keep feeding?

188
00:08:00.590 --> 00:08:03.390
Nearly every large galaxy hosts one of these

189
00:08:03.390 --> 00:08:06.150
monsters. Millions or billions of times the

190
00:08:06.150 --> 00:08:09.030
mass of the Sun. When they feed, they blast

191
00:08:09.030 --> 00:08:11.990
out enormous energy, powerful jets that heat

192
00:08:11.990 --> 00:08:14.530
the gas around them. And that's the paradox.

193
00:08:14.770 --> 00:08:17.090
That heating should cut off the black hole's

194
00:08:17.090 --> 00:08:19.970
own fuel supply. So why don't they starve?

195
00:08:20.290 --> 00:08:23.210
Avery: The leading idea has been a kind of cosmic

196
00:08:23.210 --> 00:08:25.890
recycling loop. The heated gas eventually

197
00:08:25.890 --> 00:08:28.610
cools back down, condenses into long thin

198
00:08:28.610 --> 00:08:31.410
streamers called filaments and rains back

199
00:08:31.410 --> 00:08:33.890
towards the center. Self regulating

200
00:08:34.130 --> 00:08:36.810
but Actually seeing the connection filament

201
00:08:36.810 --> 00:08:39.450
to black hole has eluded astronomers for

202
00:08:39.450 --> 00:08:40.050
decades.

203
00:08:40.590 --> 00:08:43.510
Anna: Until now. An international team led by Julie

204
00:08:43.510 --> 00:08:46.110
Hvlasic Lorando at the University of Montreal

205
00:08:46.350 --> 00:08:48.750
pointed the James Webb Space telescope at

206
00:08:48.750 --> 00:08:51.590
NGC 4696, the giant

207
00:08:51.590 --> 00:08:53.350
elliptical galaxy at the heart of the

208
00:08:53.350 --> 00:08:56.270
Centaurus cluster, about 145

209
00:08:56.270 --> 00:08:58.710
million light years away. Their results were

210
00:08:58.710 --> 00:09:00.750
published this week in the Astrophysical

211
00:09:00.750 --> 00:09:01.550
Journal Letters.

212
00:09:01.870 --> 00:09:04.630
Avery: And Centaurus, we should note, is a southern

213
00:09:04.630 --> 00:09:07.310
constellation. This galaxy cluster rides high

214
00:09:07.310 --> 00:09:09.540
in our winter sky right now, though you'll

215
00:09:09.540 --> 00:09:11.500
need a decent telescope for the galaxy

216
00:09:11.500 --> 00:09:11.900
itself.

217
00:09:12.220 --> 00:09:14.540
Anna: White. Now, Hubble had previously

218
00:09:14.540 --> 00:09:17.340
photographed a curious S shaped swirl of gas

219
00:09:17.340 --> 00:09:19.700
near this galaxy's central black hole. But

220
00:09:19.700 --> 00:09:22.140
Hubble could only show where the gas sat, not

221
00:09:22.140 --> 00:09:24.500
how it moved. So the team gave Webb's

222
00:09:24.500 --> 00:09:27.420
NIRSP instrument nearly eight hours on the

223
00:09:27.420 --> 00:09:29.940
target and mapped the motion of the gas deep

224
00:09:29.940 --> 00:09:32.060
inside the black hole's sphere of influence,

225
00:09:32.220 --> 00:09:35.020
resolving features just 30 light years across

226
00:09:35.340 --> 00:09:37.740
in a galaxy hundreds of thousands of light

227
00:09:37.740 --> 00:09:38.380
years wide.

228
00:09:38.960 --> 00:09:40.640
Avery: And the swirl turned out to be

229
00:09:41.200 --> 00:09:44.080
Anna: a spinning disk of gas wrapped around

230
00:09:44.080 --> 00:09:46.880
the black hole, nearly 800 light

231
00:09:46.880 --> 00:09:49.600
years across, with material whipping around

232
00:09:49.760 --> 00:09:52.480
at, uh, up to 600 kilometers per second.

233
00:09:52.960 --> 00:09:55.760
And here's the money shot. That disk is

234
00:09:55.760 --> 00:09:58.000
physically connected to one of the huge

235
00:09:58.000 --> 00:10:00.760
infalling filaments stretching out into the

236
00:10:00.760 --> 00:10:03.600
galaxy. They watched gas flowing along

237
00:10:03.600 --> 00:10:06.440
the filament, pouring into the disk, and from

238
00:10:06.440 --> 00:10:08.930
the disk falling onto the black hole.

239
00:10:09.330 --> 00:10:12.090
Avery: The missing link caught on camera heat the

240
00:10:12.090 --> 00:10:14.250
gas. The gas cools into filaments. The

241
00:10:14.250 --> 00:10:16.610
filaments feed the disk. The disk feeds the

242
00:10:16.610 --> 00:10:18.770
black hole. The black hole heats the gas.

243
00:10:19.090 --> 00:10:20.290
Round and round it goes.

244
00:10:20.450 --> 00:10:22.930
Anna: Havlasic Lorando said Webb is revealing that

245
00:10:22.930 --> 00:10:25.050
black holes might be the ultimate cosmic

246
00:10:25.050 --> 00:10:27.410
recyclers. And because this feeding loop

247
00:10:27.410 --> 00:10:29.850
shapes when galaxies can and can't form

248
00:10:29.850 --> 00:10:32.090
stars, understanding it is really

249
00:10:32.090 --> 00:10:35.010
understanding how galaxies, including ours,

250
00:10:35.010 --> 00:10:35.490
grow up.

251
00:10:35.950 --> 00:10:38.550
Avery: Anna, uh, time for a double bill from the

252
00:10:38.550 --> 00:10:41.070
outer solar system. Two stories,

253
00:10:41.310 --> 00:10:43.870
one spacecraft, and a dwarf planet that

254
00:10:43.870 --> 00:10:46.190
keeps on giving. First,

255
00:10:46.350 --> 00:10:49.150
scientists have detected landslides on Pluto

256
00:10:49.150 --> 00:10:50.750
for the very first time.

257
00:10:50.990 --> 00:10:53.430
Anna: This is New Horizons data, isn't it? That

258
00:10:53.430 --> 00:10:55.550
Flyby was 11 years ago this week.

259
00:10:55.870 --> 00:10:58.710
Avery: It is, and that's the delightful part. A

260
00:10:58.710 --> 00:11:00.830
paper in the journal Icarus, which has been

261
00:11:00.830 --> 00:11:03.190
making headlines this week, reports that an

262
00:11:03.190 --> 00:11:05.390
international team went back through the high

263
00:11:05.390 --> 00:11:08.130
resolution images from New Horizons lorry

264
00:11:08.130 --> 00:11:10.530
camera pictures showing Pluto's surface at

265
00:11:10.530 --> 00:11:13.450
about 300 meters per pixel and found

266
00:11:13.450 --> 00:11:16.170
six large landslides inside three impact

267
00:11:16.170 --> 00:11:19.050
craters near Sputnik Planita. That famous

268
00:11:19.050 --> 00:11:20.970
heart shaped nitrogen ice plane.

269
00:11:21.210 --> 00:11:23.690
Anna: How do you recognize a landslide on a world

270
00:11:23.770 --> 00:11:24.650
made of ice?

271
00:11:25.210 --> 00:11:27.690
Avery: Same fingerprints as Earth. Crescent shaped

272
00:11:27.690 --> 00:11:30.210
collapse scars near the crater rims. Huge

273
00:11:30.210 --> 00:11:32.850
displaced blocks of ice and debris fanning

274
00:11:32.850 --> 00:11:35.130
out across the crater floors. The team

275
00:11:35.130 --> 00:11:37.490
measured them. These slides descend one and a

276
00:11:37.490 --> 00:11:40.330
half to over two kilometers, run out as far

277
00:11:40.330 --> 00:11:42.890
as 14 and a half kilometers and the largest

278
00:11:42.890 --> 00:11:45.610
covers around 130 square kilometers.

279
00:11:45.930 --> 00:11:48.050
Anna: And landslides are everywhere else, aren't

280
00:11:48.050 --> 00:11:50.330
they? Earth, Mars, Ceres,

281
00:11:50.730 --> 00:11:53.570
asteroids, even Pluto's moon Charon showed

282
00:11:53.570 --> 00:11:56.290
evidence years ago Pluto itself was the odd

283
00:11:56.290 --> 00:11:57.650
one out which was

284
00:11:57.650 --> 00:12:00.090
Avery: genuinely puzzling because Pluto has steep

285
00:12:00.090 --> 00:12:02.940
crater walls and rugged icy terrain. All the

286
00:12:02.940 --> 00:12:05.740
right ingredients. Now the gap is filled and

287
00:12:05.740 --> 00:12:08.220
it tells us gravity driven slope processes

288
00:12:08.220 --> 00:12:10.620
are actively reshaping Pluto's frozen

289
00:12:10.620 --> 00:12:13.380
surface. Even under gravity, a fraction of

290
00:12:13.380 --> 00:12:15.620
ours. What triggered them is still open.

291
00:12:15.780 --> 00:12:18.420
Possibilities range from tectonic activity to

292
00:12:18.420 --> 00:12:19.700
meteoroid impacts.

293
00:12:19.860 --> 00:12:22.820
Anna: A world we visited for a few hours in 2015,

294
00:12:23.220 --> 00:12:25.620
still handing us firsts a decade later.

295
00:12:26.100 --> 00:12:28.940
Avery: And um, it's not done because part two of

296
00:12:28.940 --> 00:12:30.780
our Pluto double is about

297
00:12:30.780 --> 00:12:32.970
Avery: the other half of that famous pair

298
00:12:32.970 --> 00:12:35.910
Anna: of Charon, Pluto's enormous moon. So

299
00:12:35.910 --> 00:12:38.110
big relative to Pluto that the two really

300
00:12:38.110 --> 00:12:40.950
form a double world. And a study published

301
00:12:41.030 --> 00:12:43.470
Tuesday in Nature Communications says

302
00:12:43.470 --> 00:12:46.190
Charon's mountains have preserved a memory of

303
00:12:46.190 --> 00:12:47.350
a wilder youth.

304
00:12:47.590 --> 00:12:48.870
Avery: What kind of memory?

305
00:12:49.110 --> 00:12:52.030
Anna: A record of despinning across the solar

306
00:12:52.030 --> 00:12:54.990
system. Tidal forces gradually slow a body's

307
00:12:54.990 --> 00:12:57.950
rotation and as ah, the spin slows the

308
00:12:57.950 --> 00:13:00.590
body's shape relaxes stressing and

309
00:13:00.590 --> 00:13:02.790
cracking the surface. The it's long been

310
00:13:02.790 --> 00:13:05.590
theorized for Charon but clear geological

311
00:13:05.590 --> 00:13:08.430
evidence was missing. So Han, Zeng Chin

312
00:13:08.430 --> 00:13:10.670
and colleagues at ETH Zurich and

313
00:13:10.670 --> 00:13:13.350
UCLA examined the orientations

314
00:13:13.350 --> 00:13:16.150
and types of tectonic features, mountain

315
00:13:16.150 --> 00:13:18.710
ranges and faults in Aus Terra

316
00:13:18.710 --> 00:13:21.590
Sharon's northern rugged highlands. Again

317
00:13:21.590 --> 00:13:23.670
using New Horizons flyby data.

318
00:13:24.070 --> 00:13:26.230
Avery: And um, the tectonic pattern fits the de

319
00:13:26.230 --> 00:13:27.910
spinning story beautifully.

320
00:13:28.260 --> 00:13:30.460
Anna: Their modeling suggests Charon's rotation

321
00:13:30.460 --> 00:13:33.380
period was once around 14.3 hours

322
00:13:33.540 --> 00:13:36.180
and it has since slowed to today's roughly

323
00:13:36.180 --> 00:13:39.060
153 hours locked in step with

324
00:13:39.060 --> 00:13:41.700
its orbit around Pluto. That's more than a

325
00:13:41.700 --> 00:13:44.500
tenfold slowdown and the stresses from that

326
00:13:44.500 --> 00:13:46.700
transformation are etched into the mountains

327
00:13:46.700 --> 00:13:48.340
we photographed in 2015.

328
00:13:48.580 --> 00:13:51.140
Avery: Chen said the study drastically changed her

329
00:13:51.140 --> 00:13:53.380
understanding of Charon's geologic history.

330
00:13:53.900 --> 00:13:55.740
And there's a bonus finding, isn't there

331
00:13:55.740 --> 00:13:57.340
about how Charon was born?

332
00:13:57.740 --> 00:14:00.140
Anna: Yes, the way despinning and global

333
00:14:00.220 --> 00:14:02.940
contraction evolved together favors

334
00:14:02.940 --> 00:14:05.820
what's called a cold start for Charon, which

335
00:14:05.820 --> 00:14:08.340
is a real clue to the early thermal history

336
00:14:08.340 --> 00:14:11.020
of icy moons across the Outer solar system.

337
00:14:11.580 --> 00:14:14.340
So between Pluto's landslides and charon's

338
00:14:14.340 --> 00:14:17.220
slowing spin, one 11 year old dataset

339
00:14:17.220 --> 00:14:19.910
gave us two papers in a week. Not a bad

340
00:14:19.910 --> 00:14:21.030
return on a flyby.

341
00:14:21.190 --> 00:14:23.790
Avery: Our final story today, Anna, uh, comes with

342
00:14:23.790 --> 00:14:26.230
some genuinely eye widening numbers.

343
00:14:26.630 --> 00:14:29.470
SpaceX has filed its latest semi annual

344
00:14:29.470 --> 00:14:32.150
constellation status report with the U.S.

345
00:14:32.230 --> 00:14:34.510
federal Communications Commission. And

346
00:14:34.510 --> 00:14:37.230
according to coverage of the filing, StarLink

347
00:14:37.230 --> 00:14:38.390
satellites performed

348
00:14:38.470 --> 00:14:42.070
207,152

349
00:14:42.070 --> 00:14:44.390
collision avoidance maneuvers between

350
00:14:44.390 --> 00:14:46.310
December 2025 and

351
00:14:46.390 --> 00:14:48.644
May 2026.

352
00:14:48.882 --> 00:14:51.390
Anna: 207,000 in six months,

353
00:14:51.710 --> 00:14:53.390
up nearly 60,000

354
00:14:53.550 --> 00:14:55.990
Avery: on the previous half year. Put the two

355
00:14:55.990 --> 00:14:58.630
periods together and the constellation made

356
00:14:58.630 --> 00:15:00.276
over 355,000

357
00:15:00.544 --> 00:15:03.430
dodges in 12 months. More

358
00:15:03.430 --> 00:15:05.670
than triple what it performed in all of

359
00:15:05.670 --> 00:15:08.190
2024. At uh, on average,

360
00:15:08.350 --> 00:15:11.270
each Starlink satellite now swerves more

361
00:15:11.270 --> 00:15:14.150
than 40 times a year. That's nearly a

362
00:15:14.150 --> 00:15:16.260
dodge a week per satellite.

363
00:15:16.420 --> 00:15:18.900
Anna: Let's be fair to SpaceX for a moment though.

364
00:15:19.060 --> 00:15:21.460
These maneuvers are the system working as

365
00:15:21.460 --> 00:15:22.500
designed, aren't they?

366
00:15:22.660 --> 00:15:24.820
Avery: They are. The satellites dodge

367
00:15:24.820 --> 00:15:27.500
autonomously whenever the predicted collision

368
00:15:27.500 --> 00:15:30.180
probability exceeds 3 in 10 million,

369
00:15:30.420 --> 00:15:33.380
an extremely conservative threshold, far

370
00:15:33.380 --> 00:15:36.260
tighter than the industry standard. Experts

371
00:15:36.260 --> 00:15:38.900
consistently credit SpaceX with managing its

372
00:15:38.900 --> 00:15:41.500
traffic well and being transparent with the

373
00:15:41.500 --> 00:15:44.280
data. The concern is the trendline,

374
00:15:44.360 --> 00:15:45.400
not the competence.

375
00:15:45.640 --> 00:15:47.960
Anna: Because the numbers compound. More

376
00:15:47.960 --> 00:15:50.600
satellites means more close approaches means

377
00:15:50.600 --> 00:15:53.400
more maneuvers means more residual risk

378
00:15:53.400 --> 00:15:55.160
that never quite goes to zero.

379
00:15:55.640 --> 00:15:58.520
Avery: Exactly the point Huw Lewis makes. He's the

380
00:15:58.520 --> 00:16:00.600
University of Birmingham um, astronautics

381
00:16:00.600 --> 00:16:02.760
professor who's tracked these reports for

382
00:16:02.760 --> 00:16:05.640
years. Each maneuver cuts the collision odds

383
00:16:05.640 --> 00:16:08.280
to about one in a million, which sounds

384
00:16:08.280 --> 00:16:11.230
negligible, but as he puts it, if you make

385
00:16:11.230 --> 00:16:13.390
a million maneuvers with a one in a million

386
00:16:13.390 --> 00:16:16.270
residual, you end up with an aggregate risk

387
00:16:16.270 --> 00:16:18.630
across the Constellation that you simply

388
00:16:18.630 --> 00:16:21.390
can't get rid of. His blunt assessment,

389
00:16:21.550 --> 00:16:23.630
he thinks we're heading towards a situation

390
00:16:23.870 --> 00:16:26.390
where there will be a collision involving an

391
00:16:26.390 --> 00:16:28.910
operational satellite in the Constellation.

392
00:16:29.150 --> 00:16:32.110
Avery: And the projections on current growth

393
00:16:32.270 --> 00:16:35.150
Starlink passes. A million total avoidance

394
00:16:35.150 --> 00:16:37.940
maneuvers by mid2027. And by

395
00:16:37.940 --> 00:16:40.380
2030 the constellation could be making more

396
00:16:40.380 --> 00:16:42.980
than a million maneuvers every single year.

397
00:16:43.620 --> 00:16:46.100
Remember too, and regular listeners will.

398
00:16:46.500 --> 00:16:49.020
SpaceX has applied to the FCC to grow

399
00:16:49.020 --> 00:16:51.780
Starlink toward 100,000 satellites,

400
00:16:51.860 --> 00:16:53.860
a story we covered a couple of weeks back.

401
00:16:54.340 --> 00:16:56.540
And it's not alone up there. Amazon's

402
00:16:56.540 --> 00:16:58.980
Constellation and China's Qian Fan are

403
00:16:58.980 --> 00:17:00.420
actively deploying as well.

404
00:17:00.740 --> 00:17:03.300
Anna: The number of operational spacecraft in orbit

405
00:17:03.300 --> 00:17:05.380
has gone from about 10,000 to about

406
00:17:05.460 --> 00:17:08.210
16,000 in just a year. Other

407
00:17:08.210 --> 00:17:10.570
experts are calling for operators to disclose

408
00:17:10.570 --> 00:17:12.530
predicted maneuver counts before

409
00:17:12.610 --> 00:17:15.090
Constellations are even approved. Though

410
00:17:15.090 --> 00:17:17.210
regulators know whether the satellites can

411
00:17:17.210 --> 00:17:19.930
Avery: actually keep up, low Earth orbit is a

412
00:17:19.930 --> 00:17:22.330
shared resource. And this is the traffic

413
00:17:22.330 --> 00:17:24.370
report. We'll keep watching the numbers

414
00:17:24.370 --> 00:17:27.090
because everyone from astronomers to airlines

415
00:17:27.090 --> 00:17:29.770
to your GPs depends on that neighborhood

416
00:17:29.770 --> 00:17:30.610
staying safe.

417
00:17:30.930 --> 00:17:33.610
Anna: Time now for tonight's skywatching. And for

418
00:17:33.610 --> 00:17:35.810
our Southern Hemisphere friends, the news is

419
00:17:35.810 --> 00:17:38.650
good. The Moon is a waning crescent rising in

420
00:17:38.650 --> 00:17:40.930
the small hours, so evenings this week are

421
00:17:40.930 --> 00:17:43.330
dark and glorious, which means

422
00:17:43.330 --> 00:17:46.290
Avery: the winter Milky Way at its absolute best

423
00:17:46.770 --> 00:17:48.730
face south after dinner. And the galactic

424
00:17:48.730 --> 00:17:51.570
core in Sagittarius and Scorpius is almost

425
00:17:51.570 --> 00:17:54.130
directly overhead from most of Australia and

426
00:17:54.130 --> 00:17:57.010
New Zealand dust lanes. Star clouds, the

427
00:17:57.010 --> 00:17:59.450
lot. If you can get away from city lights

428
00:17:59.450 --> 00:18:01.770
this week, do it while you're there.

429
00:18:01.770 --> 00:18:04.050
Anna: Sweep up Omega, uh, Centauri and the Southern

430
00:18:04.050 --> 00:18:06.300
Cross riding high. And if you've got

431
00:18:06.300 --> 00:18:08.340
binoculars, the star fields between

432
00:18:08.340 --> 00:18:11.100
Scorpius's tail and the teapot of Sagittarius

433
00:18:11.180 --> 00:18:14.060
will keep you busy all evening. Saturn

434
00:18:14.060 --> 00:18:16.300
is climbing in the east by mid evening for a

435
00:18:16.300 --> 00:18:18.860
late night treat. And dazzling Venus still

436
00:18:18.860 --> 00:18:21.100
rules the early evening western sky.

437
00:18:21.499 --> 00:18:24.380
Avery: And one for the launch watchers. SpaceX's

438
00:18:24.380 --> 00:18:27.340
Starship Flight 13 window opens tonight,

439
00:18:27.340 --> 00:18:29.980
US time. That's tomorrow morning for us

440
00:18:30.140 --> 00:18:32.670
from about 8:45 aesthetic.

441
00:18:33.060 --> 00:18:35.580
So pour a coffee and watch this space. We'll

442
00:18:35.580 --> 00:18:37.700
have the full story in Saturday's weekend

443
00:18:37.700 --> 00:18:38.100
wrap.

444
00:18:38.420 --> 00:18:40.460
Anna: That's it for today's episode. Thanks for

445
00:18:40.460 --> 00:18:43.140
joining us. You can find show notes, links to

446
00:18:43.140 --> 00:18:45.818
every story and our back catalog@ah,

447
00:18:46.102 --> 00:18:48.939
astronomydaily.IO and we're astronomy

448
00:18:48.939 --> 00:18:50.740
Daily Pod on all the socials.

449
00:18:51.140 --> 00:18:53.780
Avery: Astronomy Daily is part of the bytes.com

450
00:18:53.860 --> 00:18:55.780
podcast network. I'm um, Avery.

451
00:18:55.860 --> 00:18:58.340
Anna: And I'm Anna. We'll see you tomorrow. Until

452
00:18:58.340 --> 00:19:00.100
then, clear skies.