Scope-city. Not one but two of the world’s greatest telescopes.

A massive weekend for a massive telescope, a chance to shine a light on the stuff that doesn’t shine, & an old beauty reminds us why she’s so cool with possibly the most awesome images I’ve ever seen.

(First published on my Substack where you can get #NerdNews, marvellous maths and general geekery.)

(Roman takes to the skies: coutrtesy NASA)

Roman across space.

On Sunday night, the Nancy Grace Roman Space Telescope blasted off from Cape Canaveral, carried by a SpaceX Falcon Heavy. And the Aussie nighttime launch allowed space nerds to watch the footy, tuck in a dinner, then drag the kids over to the screen to witness a $4 billion observatory leave the planet.

If you had May of next year pencilled in your diary, yes, Roman is nine months ahead of schedule. Stunning, given that the James Webb telescope ran fourteen years late.

Seeing what we can’t see.

I love reflecting on the fact that everything I will ever see, touch, photograph or smell comprises only 5 per cent of the “stuff” that makes up the universe. The other 95 per cent is made up of dark matter (27 per cent) and dark energy (68 per cent).

“What law governs the universe on its largest scales?” — Mustapha Ishak, cosmologist, University of Texas at Dallas.

It is understandable you would ask. If we can’t see it, how do we know it’s there? It all comes down to us observing the universe behaving in ways that it simply wouldn’t if everything we could see, smell, touch, etcetera was all there was.

Fritz Zwicky, (quick moment to pause and reflect on one of the coolest names in the history of science), looked at the Coma cluster in the 1930s and worked out the galaxies were moving far too fast for the visible mass to hold them together. They should have flown apart.

Pair that observation with this gem from four decades later. Vera Rubin and Kent Ford measured the speed of rotation of spiral galaxies (spoiler alert, there’s a couple of cracking photos of spiral galaxies later in this article). Turns out the outer stars were rotating at the same speed as the inner ones.

If there was only what we could see, smell, touch, etcetera, as matter, it should behave more like our solar system, where the outer planets orbit more slowly than the inner ones. The conclusion our physicists drew was that something must be out there. Something invisible, adding mass.

That, my friends, is what we call dark matter.

How heavy? Check the stretch marks.

You’ve probably heard of the concept that mass bends light. Well, it turns out it doesn’t matter whether we can see that mass or not. It still does the bending.

This is the secret to weak gravitational lensing, which lies at the heart of what Roman will do.

By looking at numerous galaxies and analysing whether the light we receive has been distorted in the same direction, we can assume there must be dark matter present between us and those galaxies.

And the really cool thing is the size of the number.

Roman will be helping us observe more than two billion galaxies, that’s billions with a ‘b’, covering about one eighth of the entire sky. This is one of the largest samples any similar observation has analysed. Add in the fact that Roman sits above the atmosphere, which lets it measure the shapes of galaxies far more precisely than telescopes on the ground can, and we get far and away our best look yet into the world of dark matter.

“We’ll redefine what it means to find a needle in a haystack.” — Julie McEnery, Roman senior project scientist, NASA Goddard.

Over the next five years, Roman will be snapping away happily with its 300 megapixel camera. But before you think, ‘hey, that’s only about six times bigger than my iPhone’, the real payoff is the size of the mirror the light bounces off before it reaches those megapixels.

Roman’s mirror is 2.4 metres across, the same as Hubble’s, and it gathers something like a hundred thousand times more light than the lens on your phone. That combination means Roman sees as sharply as Hubble does, but photographs at least 100 times more sky in a single shot.

(Roman Enclosed in SpaceX Falcon Heavy Rocket Fairing NASA/Sydney Rohde (Rocz))

It sits 1.5 million kilometres from Earth, always on the night side, moving around the sun in step with us. From out there it beams back about 1.4 terabytes a day, the equivalent of streaming around 350 feature films. And Aussies, you can be proud knowing some of that data comes down to a 35 metre dish in Western Australia, at a place called New Norcia.

Sweet Sixteen (Galaxies).

And as we focus on a newbie, a quick shout out to the phenomenal Chandra telescope. It launched in 1999 aboard the space shuttle Columbia and has been NASA’s flagship X-ray observatory ever since.

Chandra supplies the X-ray data, which scientists then combine with images from telescopes you have heard of, Webb and Hubble among them, to build a single picture.

It captures a hot, violent universe of superheated gas clouds, ravenous black holes and exploded stars. This week the Chandra X-ray Center released sixteen new galaxy images, each one combining X-ray data gathered over decades with those other observations. Spirals, ellipticals and irregulars.

Light reflects off a surface. X-rays hitting one head on are absorbed, so Chandra’s mirrors are nested barrels angled to let X-rays skim along them instead. And in capturing X-rays rather than light, Chandra sees far more violent energy. Think of Roman photographing the stars, and Chandra the violence swirling around them.

(Sixteen galaxies imaged by Chandra, combining X-ray data gathered over decades with observations from Webb, Hubble and others. Image: NASA/CXC/SAO)

Check out the sixteen beauties, including three of my favourites: M104, the Sombrero, second row far right, seen dead edge-on so you get the dust lane in profile; NGC 3938, bottom row third across, a face-on spiral with arms you can trace all the way round; and Arp 143, third row far left, two galaxies caught mid-collision with the wreckage still spreading. I mean seriously, that’s what we are looking at. Chandra, you beast!

Don’t switch it off just yet.

As with so many flagship science programs in the United States of late, an ominous funding axe may be hanging over Chandra.

“I’m horrified by the prospect of Chandra being shut down prematurely.” — Andrew Fabian, X-ray astronomer, University of Cambridge, speaking in 2024.

I for one hope it’s around for decades to come producing more amazing images like this.

Further reading:

Chandra X-ray Center, “Galactic Gems Glisten in New Gallery From NASA’s Chandra”, 25 August 2026.

NASA, the Nancy Grace Roman Space Telescope core community surveys.

New NASA photos reveal 16 galaxies from across the cosmos in dazzling detail, Mary Randolph, Scientific American, 2026.

Core Survey by NASA’s Roman Mission Will Unveil Universe’s Dark Side, NASA, 2026.

Cutting-edge infrared space telescope Roman set to launch, European Space Agency, 2026.