Penguins, rings, storms - JWST 2nd anniversary

Following on from the previous post, the beady eye of the James Webb Space Telescope has just celebrated its 2nd year of peering into space, unveiling secrets about everything from Jupiter's atmosphere to galaxy collisions and black holes. What does this have to do with penguins and rings in the sky? Well, read on to find out. In this article, I have written about the photos in decreasing size order, starting from galaxies, then an individual galaxy, then coming much closer to home with a nearby planet.

Penguin and Egg galaxies

Also known as NGC 2936 and NGC 2937, this penguin and egg are not residents of Antartica, but a pair of interacting galaxies who have been dancing around each other for about 50 million years. Their shapes will have been changing over millions of years as they each pull gravitationally on the other. The Penguin was previously a spiral galaxy, which was stretched through the gravitational pull of the nearby Egg, so that it now resembles a penguin with its galactic centre gleaming like an eye, and its once spiral arms unwound to shape a beak, head, body and tail. As the galaxies got closer, the Penguin's thinnest areas of gas and dust were pulled by the gravity of the Egg galaxy, causing them to crash in waves and form new stars. The smoky appearance around these newborn stars is the leftover dust from this wave of star formation. By contrast, the Egg was previously an elliptical galaxy, a type which are filled with aging stars and little gas. Its shape has hardly changed because the lack of gas means there is little dust that can be pulled away to form new stars.

Penguin and Egg, a pair of interacting galaxies. Image credit: NASA/ESA/CSA

In a few hundred million years, these galaxies will merge completely into a single massive galaxy. This energetic crash will smash millions of stars and interstellar gas into one big dusty soup of fireworks. While this may destroy star formation in some areas as gas is thrown out into the intergalactic medium, the fresh activity and injection of vast amounts of energy may kickstart future star formation in other parts of the new galaxy. These new stars will be different in chemical composition from their predecessors, having formed in different gaseous conditions.

In case anyone is worried about other galaxies smashing into our Milky Way, yes that is on course to happen with our neighbouring Andromeda galaxy. However, given Andromeda is currently 2.5 million light years away, this is not an imminent threat and any collisions won't happen for another 4 billion years or so, by which time the Sun will probably be winding down its operations anyway.

Jewelled Ring: quasar RX J1131-1231 gets magnified

Rather appropriately for summer, given it seems to be wedding season for many, the Webb telescope recently snapped this beautiful photo which looks like a glittering ring in the sky. This is a quasar, an extremely bright active galactic nucleus, called RX J1131-1231 which lives 6 billion light years away. The light is indirectly caused by a supermassive black hole in its centre, which weighs millions of times more than our Sun, and is surrounded by a huge amount of gas known as an accretion disc. Gas in this disc is pulled inwards by the black hole's strong gravity, and as it falls in at tremendous speeds, the extreme friction causes the gas to heat up and release light, which is what we can see in the photo below.

There is only one quasar in this image, but the optical illusion is caused by a phenomenon called gravitational lensing. It works like this: imagine looking in a straight line at an object (A), with a massive galaxy (B) in between your eye and A. Galaxy B is so massive that it actually bends the space around it (its a physics thing, which sounds mad but is genuinely real), so that light rays coming from A to your eye can't travel in a straight line but are bent around B. In this way, galaxy B acts like a natural lens for A, magnifying it and warping its image. This is actually a very useful tool for astronomers, as it magnifies faraway galaxies and shows hidden details that would otherwise be too small or faint to see at such long distances. In this case, the small blue dot at the ring's centre is the foreground galaxy that has acted as the lens (B), which has magnified and distorted the quasar's image (A) to make it appear as ring with multiple images of the same quasar. While no doubt a stunning image, observations like these also help astronomers understand more about the nature of black holes, and mysterious dark matter.

A distant quasar is magnified by gravitational lensing. Image Credit: ESA/Webb, NASA & CSA, A. Nierenberg

Jupiter's Great Red Spot

And finally, the biggest planet in our solar system, Jupiter, has been one of the nearer objects of interest for the Webb telescope. The planet's Great Red Spot, a massive storm that has been raging for hundreds of years, has been found to contain intricate structures and violent atmospheric activity, seen from its dark arcs and bright spots.

The bright northern and southern lights visible at the poles of Jupiter are the same phenomenon that causes aurorae on Earth - highly energetic solar particles smashing into the planet's atmosphere, being accelerated by magnetic fields towards the poles where the field is strongest, and colliding with atmospheric molecules, which become excited and emit light. While this light is easily seen by most telescopes, the faint glow of the planet away from its poles was until recently harder to detect, although now the Webb telescope with its infrared capabilities allows scientists to peer in detail at the upper atmosphere. The light from the Great Red Spot is not just driven by reflected sunlight; other mechanisms are also causing it to change shape and structure in the upper atmosphere. Gravity waves, something I briefly covered in my Astronomical Fluid Dynamics module, occur when a fluid such as a gas is displaced from its equilibrium position. Restoring the fluid's position back to equilibiurm produces a gravity wave, a series of oscillations back and forth in the fluid. These waves are generated deep in Jupiter's turbulent lower atmosphere and travel through the gas, changing the structure and features of the upper atmosphere, producing the intricate features visible. Future observations are planned to investigate the atmospheric behaviour of Jupiter further, and what better place to do it than on a striking red spot where wind speeds reach 400mph in the biggest storm in the solar system.

Jupiter and its Great Red Spot. Image credit: ESA/Webb, NASA & CSA, H. Melin, M. Zamani (ESA/Webb)