Andrew Dunkley and Professor Fred Watson cover four big astronomy stories in this episode, from Fred’s trip to view a sunset eclipse in Spain to the launch of the Nancy Grace Roman Space Telescope. They also unpack a starless dwarf galaxy called Cloud Nine and a new way of thinking about the strange dark material in Venus’s clouds.
Guests and speakers
Andrew Dunkley - Host, frames the news, asks listener questions, and guides the discussion.
Professor Fred Watson - Astronomer at large, explains the eclipse, the Roman telescope, Cloud Nine, and Venus’s clouds.
Key topics
In this episode, Fred recounts the Spanish eclipse expedition
The eclipse was only 9 degrees above the western horizon at totality, making the viewing conditions unusually challenging.
He and Marnie led a 16-person tour through France, Spain, and Switzerland before settling near Santander in northern Spain.
They staked out a viewing site 2 kilometers from the hotel, set up a gazebo, and had to tie it down to a car to keep it from blowing away.
The weather looked threatening, but a hole opened in the cloud just before totality, giving them a clear view of the corona.
Fred described the yellowish corona, pink hydrogen clouds, and the crowd of around 2,000 people.
We discuss the Nancy Grace Roman Space Telescope launch
Andrew watched the launch live after being nudged by his own brain at the right moment.
Fred noted the launch was flawless, with 27 Merlin motors firing.
The telescope is headed for the L2 Lagrange point, about 1.5 million kilometers away.
Roman is a 2.4-meter Hubble-class telescope but with 100 times the field of view.
Its wide-angle infrared design should enable major surveys of dark matter, dark energy, and exoplanets via its coronagraph.
Fred explains why Cloud Nine matters
Cloud Nine is described as a starless dwarf galaxy about 14 million light years away.
It lies near Messier 94 and was studied using the Gran Telescopio Canarias and its Hypercam instrument.
The deep exposure was 2.36 hours, yet the team found no convincing stellar population.
Fred says theory suggests the gas may be too hot to cool and collapse into stars because of the ultraviolet background radiation after reionization.
He says Cloud Nine may be the first strong example of a galaxy predicted by standard cosmology but never before clearly identified.
Venus’s clouds are still puzzling astronomers
Fred explains that Venus appears yellowish because we see the top of its cloud layer, especially in visible light.
In ultraviolet, Venus shows dramatic global cloud patterns caused by an as-yet unidentified absorber.
The new study uses radiative transfer modeling to constrain what the unknown absorber could be.
The team compares Venus’s cloud droplets to cigarette smoke, tiny particles that look light-colored when dispersed but could become dark sludge in bulk.
The result suggests the absorber must be very efficient, very concentrated, or both, but it is not being claimed as evidence of life.
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