Associate Professor of Earth and Planetary Science at Washington University in St. Louis | Planetary Evangelist | he/him/Professor | 🇮🇪 in 🇺🇸
Feb 10 • 6 tweets • 2 min read
This. Is. Amazing.
NASA's #ParkerSolarProbe was able to image the surface of #Venus from space in a way we didn't think possible before!
Here, we can see the Aphrodite Terra highland *glowing* through the clouds (left), exactly where radar data tell us it should be (right)!
Venus' thick cloud layer obscures the surface from space at visible wavelengths—but there are some "windows" at near-infrared wavelengths where cameras can see through to the surface.
PSP took these images at a wavelength not thought to be able to penetrate the clouds before.
Jan 16 • 4 tweets • 1 min read
A quick 🧵 about the *size* of the #HungaTonga eruption:
Volcanic eruptions are generally assigned a VEI—Volcanic Explosivity Index—value.
This scale is a general indicator of the explosive character of an eruptive event.
This scale, described by Christopher Newhall and Stephen Self in a 1982 paper, is a general indicator of the explosive character of an eruptive event, and reflects the interplay of an eruption's magnitude, intensity, and energy release rate.
Aug 28, 2021 • 8 tweets • 2 min read
I need you to know I'm being completely serious here.
We have no idea what's inside Uranus.
We really don't have a clue what's inside this or there other "ice giant", Neptune.
It's possible that there's a rocky interior, perhaps at least as large as Earth. There might be a water–ammonia ocean above that rocky centre, topped with a thick atmosphere.
But we don't know.
Aug 26, 2021 • 6 tweets • 2 min read
The Solar System is *full* of incredible and fascinating worlds!
Uranus and Neptune.
Ceres, Vesta, and the other main asteroid belt bodies.
The myriad other minor bodies scattered across the System.
Every one of them amazing! 🥰
People are pointing out that I forgot somewhere important!
Somewhere that fascinates everyone, that we need to explore more, that holds a special place in our heart.
First off: what *are* the tesserae (sing. "tessera")?
In short: dunno! Ha.
The longer answer is that they're very heavily tectonically deformed rocks, and where they're found they're the oldest things around: everything else is on top of them.
Here's what they look like:
Sep 16, 2020 • 12 tweets • 7 min read
Things have quietened enough that I'm going to share my thoughts about the detection of #phosphine on #Venus announced yesterday.
In short: this is a BIG fucking deal. And here's why:
Phosphine (PH₃) is a fairly rare gas. It forms in giant planets, like #Jupiter, because of the extreme conditions inside them (and because of their hydrogen-rich atmospheres). Neither condition applies to Venus.
PH₃ is also produced by biological activity.
May 18, 2020 • 8 tweets • 4 min read
At 8:32 am Pacific time, May 18, 1980, it happened.
#MountStHelens exploded, producing the largest landslide ever recorded, sending a tower of rock and ash 19 km into the stratosphere, and killing 57.
I've added the Empire State Building to this image for scale.
A shallow earthquake caused the entire northern flank of the volcano to slide. The reduced pressure allowed a huge "cryptodome" of hot, pressurised magma inside the volcano to explode—creating a lateral blast that flattened trees for tens of kilometres.
Because I'm procrastinating, here's a short thread on the geology of some of the locales around Ireland, as shown by this map
First up: the Wicklow Mountains (white box on map to the right).
These mountains are a) actually not really mountains at all (just big hills), and b) exposed granite intrusions that were pushed up when an ancient ocean called Iapetus closed up ~420 Myr ago (plus or minus)
Apr 12, 2020 • 7 tweets • 3 min read
As people are tucking into Easter eggs today, here's a list of some of the *absolute worst* substitutes for chocolate eggs that #geology can offer you. Consider yourself warned.
Type: onion-skinned weathering of massive rocks (including sandstones and granites).
How: formed by weathering along spheroidal fracture planes within the rock mass
Why is bad: it's rock, so will break your teeth, and doesn't at all taste like chocolate
@NASA has picked four missions for detailed, 9-month studies under the Discovery-class cost cap; one or two mission finalists will be actually selected for flight around the end of the year.
The first is DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus), which is a mission to take detailed chemical measurements as it plunges through the Venus atmosphere!
And we're pivoting away from landing sites now and turning to cloud habitability - with the first talk given by Michael Way, about possible conditions on early #Venus!
The next talk is from Shawn Domagal-Goldman, who's describing (remotely, from the US!) how #Venus offers us a useful natural laboratory to understand planetary habitability in general