“The King of Siam, an honourary member, reported as dead, is still alive” Spotted in an old @royalastrosoc.bsky.social paper. #astronomy 🧪

Mars’s moon Phobos set against the Red Planet. At an average diameter of just 22km across, it is smaller than a city. (Although I always say it looks like a giant space potato). #astronomy 🧪 Image: Mars Express

One of Carl Sagan’s most famous lines compares Earth to a mote of dust suspended in a sunbeam. But it wasn’t his. He pinched it from Sir James Jeans, who wrote in the 1930s: “our Earth will look smaller than the tiniest of motes in a sunbeam” #astronomy ⚛️🧪 Image: NASA/JPL

I’ll be live in an hour, talking about the future of human missions to Mars. Rockets, radiation, dust storms and what it will actually take to live on another planet. Got a question about Mars? Leave it here and I’ll try to answer it live. 8pm UK / 4pm ET open.substack.com/live-stream/... 🔭⚛️🧪

Julius Caesar was famously murdered on this day in 44BCE. Four months later, a comet blazed across the daytime sky in Rome. Some thought it was Caesar’s soul. A cult grew around the comet & eventually it appeared on Roman silver coins. 🧵 (1/2) 🔭🧪⚛️ #history 📸 Classical Numismatic Group/ NASA

The IceCube detector in Antarctica detected three high energy neutrinos nicknamed Bert, Ernie & Big Bird. Big Bird’s energy was a billion times bigger than a dental X-ray, jammed into a particle with a mass less than a millionth of an electron. #astronomy ⚛️🧪 Image: IceCube Collaboration

A cosmic ray once hit the Earth so hard astronomers named it the Oh My God particle. It had travelled 1.5 billion light years to reach us. But it was travelling so close to light speed that from its perspective the journey took a mere 1.7 days. #astronomy ⚛️ 🧪

We’re going back to the Moon in April, could Mars be next? Come and find out how we might pull it off and the obstacles that still stand in our way. This Sunday 8pm UK / 4pm ET Livestream: open.substack.com/live-stream/... (Calendar links below) #astronomy 🧪⚛️

Jules Verne is one the few craters on the Moon named after someone’s full name. Normally it’s just their surname (or occasionally first name for megastars like Tycho). Image: LRO #astronomy 🧪

The peak of Everest isn’t the highest on Earth. At least if you’re measuring from the planet’s centre. That honour falls to Mount Chimborazo in Ecuador. It’s close to the equator, where the Earth bulges outwards as it spins. 🔭🧪⚛️ Image: Eduardo Navas

Mars is cold enough to freeze your blood, dusty enough to choke machines & bathed in radiation. Yet we’re planning to send people there. This Sunday I’m giving a live talk on how humans might survive the Red Planet. 8pm UK / 4pm ET open.substack.com/live-stream/... (Calendar links below) ⚛️ 🧪 🔭

The Tropic of Cancer is drifting southwards by about 15 metres every year. Some Mexican highways used to have signs marking the changes. The shift happens because Earth’s axial tilt is slowly decreasing, due to gravitational tugs from the Sun and Moon. #astronomy 🧪 ⚛️ 📷 Roberto González

Meteorites scattered across a blue-ice moraine in Antarctica’s Miller Range. They’re easier to find here because glaciers act like slow conveyor belts, carrying meteorites toward mountain ranges where wind strips away the snow and exposes the ice. #astronomy ⚛️ 🧪 Image: NASA

NASA’s Genesis mission crash-landed back on Earth because an accelerometer was installed backwards. Despite the impact, scientists still managed to recover some of the solar wind particles trapped inside. #astronomy 🧪 ⚛️ Image: USAF 388th Range Squadron

In 1932, two newlyweds packed a folding kayak with: • hard-boiled eggs • chocolate • strawberries • two bottles of brandy Then they pushed out into the Black Sea as refugees from the Soviet Union. 🧵 (1/8) 🔭 ⚛️ 🧪 #histsci Image: George Gamow

Mercury and Venus photobombing our view of the Sun. The Sun itself is hiding behind the central white circle and you can clearly see it spewing hot plasma into space. #astronomy 🧪 ⚛️ Credit: NASA/Goddard Space Flight Center

1 hour to go until @ryanjfrench.bsky.social joins me live to discuss solar flares and space weather. Join us at 8pm UK / 4pm ET / 1pm PT open.substack.com/live-stream/... 🧪 ⚛️ 🔭

Saturn’s moon Pan looks like a raviolo. Its distinctive equatorial ridge is likely due to material the moon has swept up from Saturn’s rings. #astronomy 🧪 Image: NASA/JPL-Caltech/Space Science Institute

Meet the greatest time traveller in human history. Oleg Kononenko has spent more than 1000 days in orbit. Moving at 28,000 km/h, relativity means he’s travelled 0.025 seconds into the future. 🔭 🧪 ⚛️ Image: Johnson Space Center / NASA / Andrey Shelepin

A single solar flare can unleash the energy of 10 million volcanic eruptions. Find out more this Sunday when solar flare expert Ryan French joins my Sunday Space Sessions. 8pm UK / 4pm ET Livestream: open.substack.com/live-stream/... (calendar links below) #astronomy 🧪 ⚛️

This quasar is surrounded by a cloud containing 140 trillion times more water than all of Earth’s oceans. #astronony 🧪 Image: NASA/ESA

Where is Hell? On the Moon. It’s a 32km impact crater in the lunar southern hemisphere. Named after Hungarian astronomer and Jesuit priest Maximilian Hell. #astronomy 🧪 Image: Lunar Orbiter 4

Physicist Andrei Linde once wooed a girl with outlawed Stalinist poetry. “I kept [her] hand in mine just a second longer than I was supposed to… months later we married.” The girl was Renata Kallosh. Together they reshaped cosmology, from inflation to string theory. 🔭 🧪 ⚛️ 📷: Merlijn Doomernik

The Earth and Moon as seen by the fleeing Galileo spacecraft from a distance of 6 million kilometres. Both Antartica and the Moon’s own South Pole Aitken basin are visible. #astronomy 🧪 Image: NASA

This Sunday, @ryanjfrench.bsky.social joins me to discuss one of the solar system’s most dramatic phenomena: solar flares. What causes them? Do they threaten Earth? What don’t we know? Join us at 8pm UK / 4pm ET open.substack.com/live-stream/... (Calendar links below) #astronomy ⚛️🧪

Look how thin the rings of Saturn are. They appeared to almost disappear as the Cassini spacecraft crossed their plane. Saturn’s moon Enceladus even pops up in the background. #astronomy 🧪 Image: NASA / JPL / SSI / Gordan Ugarkovic

Caroline Herschel once showed princesses a fake Saturn through her telescope at Windsor Castle. On the night of 3 July 1782, the plan was to show the royals Jupiter or Saturn. But the weather was not favourable. Luckily, Caroline had prepared… 🧵 (1/3) #astronomy #histsci 🧪

A strange ‘zebra’ rock found on Mars by the Perseverance rover. About 20cm long, scientists speculate that it could be volcanic in origin. #astronomy 🧪 Image: NASA/ JPL-Caltech/ ASU

Astronomer Nevil Maskelyne racked up a £141 alcohol bill during his 18 month expedition to observe the 1761 Transit of Venus. That’s over £26,000 ($35,000) in today’s money. Or almost £50 per day. He claimed it on expenses and would go on the become Astronomer Royal. #astronomy #histsci 🧪

Venus disappearing behind the craggy lunar surface. Astronomers call this an occultation. When stars pass behind distant solar system objects, extra dips in the starlight before and after the main blackout can reveal hidden details. 🧵 (1/2) Image: Quentin Gineys #astronomy 🧪

I’m live in an hour with The Ultimate Guide to Time Travel. 8pm UK / 3pm ET Important: if you previously added the talk to your calendar, the streaming link has been updated. Join here: open.substack.com/live-stream/... #astronomy 🧪 ⚛️

Close to Mars’s North Pole you’ll find basaltic sand dunes. They’re covered with a seasonal carbon dioxide frost. #astronomy 🧪 Image: NASA/JPL-Caltech/Univ. Of Arizona

A rare view of Jupiter’s faint rings. Unlike Saturn’s more famous icy rings, Jupiter’s are made of dust. The dust was created when impacts battered the planet’s inner moons. #astronomy 🧪 Image: NASA, ESA, CSA, Jupiter ERS Team; image processing by Ricardo Hueso (UPV/EHU) and Judy Schmidt.

Jupiter’s moon Callisto is famous for its multi-ring impact craters. This is Valhalla, where the rings extend 1900km from the centre. That’s roughly the distance between Texas and Canada. #astronomy Image: NASA, Calvin J. Hamilton

The Sun has beaches (sort of). Plages - from the French word for beaches - are bright, hot and dense regions of the Sun’s chromosphere. You normally find them around darker sunspot areas. #astronomy Image: John W. Evans Solar Facility/Sacramento Peak Observatory

If you could only use a time machine once - would you go forwards or backwards? This Sunday I’m breaking down what relativity actually permits and where paradoxes start to bite. 1 March 8pm UK / 3pm ET Livestream: open.substack.com/live-stream/... (1/2) #astronomy #physics

This snaking line on the Moon is a path carved by lava 2.5 billion years ago. Known as Vallis Schröteri, it’s a sinuous rille that meanders for more than 160km. (1/2) #astronomy Image: NASA/LRO

A gorgeous view of two colliding galaxies from JWST. NGC 2207 and IC 2163 will slowly merge over billions of years. #astronomy Image: NASA/ESA/CSA

The nighttime River Nile delta seen from space. The lights are a perfect illustration of how important water is to us and all life on Earth. #astronomy Image: NASA Earth Observatory

Puts me in mind of Halley's depiction, from 1715

A total solar eclipse seen from space. The shadow of the Moon looks like a giant bruise from the perspective of the astronauts aboard the ISS. #astronomy Image: NASA

Is time travel actually possible? Modern physics has a surprisingly clear answer. This Sunday I’ll be explaining what relativity really allows and the paradoxes that could stand in the way. 8pm UK / 3pm ET Livestream: open.substack.com/live-stream/... (1/2) #astronomy #scicomm

A close-up of Comet 67P/C-G with a tiny piece of debris in tow (circled). This mini-satellite, just 4 metres across, has been dubbed Churymoon. #astronomy Image: ESA

Astronauts sometimes become aquanauts. There’s an Aquarius Reef Base on the seabed off the Florida Keys. Astronauts live there more than two weeks and activities include simulated space walks. #astronomy Image: NASA

This is how they clean the mirrors of the Very Large Telescope in Chile. With a carbon dioxide snow gun. It creates tiny explosions that carry dust away. 🧵 (1/2) #astronomy Image: ESO/Max Alexander

Curiosity found what looks like a doorway on Mars. But it’s an optical illusion. A combination of a well placed shadow and a fracture that could have been caused by a Marsquake. #astronomy

This looks like an ordinary solar eclipse, but it isn’t. That’s not the Moon blocking the Sun - it’s the Earth. The image was taken by Firefly Aerospace’s Blue Ghost lunar lander from the surface of the Moon. #astronomy

Saturn’s moon Titan casting a shadow onto the ringed planet. The moon is fittingly named - it’s larger than the planet Mercury. #astronomy Image: NASA/JPL/Space Science Institute

My Astronomy Q&A livestream starts in one hour. Come and ask me anything about the universe. 22 Feb - 8pm UK / 3pm ET Join here: open.substack.com/live-stream/... #astronomy

This is a jellyfish galaxy. It has a long tail of gas, pockmarked with starbursts. It’s travelling fast through a cluster of galaxies and the interaction with its surroundings pulls out the tentacles. #astronomy Image: NASA, ESA, CXC