5 Unpredictable Things Swift Has Studied (and 1 It’s Still Looking For)
Our Neil Gehrels Swift Observatory — Swift for short — is celebrating its 20th anniversary! The satellite studies cosmic objects and events using visible, ultraviolet, X-ray, and gamma-ray light. Swift plays a key role in our efforts to observe our ever-changing universe. Here are a few cosmic surprises Swift has caught over the years — plus one scientists hope to see.
#BOAT
Swift was designed to detect and study gamma-ray bursts, the most powerful explosions in the universe. These bursts occur all over the sky without warning, with about one a day detected on average. They also usually last less than a minute – sometimes less than a few seconds – so you need a telescope like Swift that can quickly spot and precisely locate these new events.
In the fall of 2022, for example, Swift helped study a gamma-ray burst nicknamed the BOAT, or brightest of all time. The image above depicts X-rays Swift detected for 12 days after the initial flash. Dust in our galaxy scattered the X-ray light back to us, creating an extraordinary set of expanding rings.
Star meets black hole
Tidal disruptions happen when an unlucky star strays too close to a black hole. Gravitational forces break the star apart into a stream of gas, as seen above. Some of the gas escapes, but some swings back around the black hole and creates a disk of debris that orbits around it.
These events are rare. They only occur once every 10,000 to 100,000 years in a galaxy the size of our Milky Way. Astronomers can’t predict when or where they’ll pop up, but Swift’s quick reflexes have helped it observe several tidal disruption events in other galaxies over its 20-year career.
Active galaxies
Usually, we think of galaxies – and most other things in the universe – as changing so slowly that we can’t see the changes. But about 10% of the universe’s galaxies are active, which means their black hole-powered centers are very bright and have a lot going on. They can produce high-speed particle jets or flares of light. Sometimes scientists can catch and watch these real-time changes.
For example, for several years starting in 2018, Swift and other telescopes observed changes in a galaxy’s X-ray and ultraviolet light that led them to think the galaxy’s magnetic field had flipped 180 degrees.
Magnetic star remnants
Magnetars are a type of neutron star, a very dense leftover of a massive star that exploded in a supernova. Magnetars have the strongest magnetic fields we know of — up to 10 trillion times more intense than a refrigerator magnet and a thousand times stronger than a typical neutron star’s.
Occasionally, magnetars experience outbursts related to sudden changes in their magnetic fields that can last for months or even years. Swift detected such an outburst from a magnetar in 2020. The satellite’s X-ray observations helped scientists determine that the city-sized object was rotating once every 10.4 seconds.
Comets
Swift has also studied comets in our own solar system. Comets are town-sized snowballs of frozen gases, rock, and dust. When one gets close to our Sun, it heats up and spews dust and gases into a giant glowing halo.
In 2019, Swift watched a comet called 2I/Borisov. Using ultraviolet light, scientists calculated that Borisov lost enough water to fill 92 Olympic-size swimming pools! (Another interesting fact about Borisov: Astronomers think it came from outside our solar system.)
What's next for Swift?
Swift has studied a lot of cool events and objects over its two decades, but there are still a few events scientists are hoping it’ll see.
Swift is an important part of a new era of astrophysics called multimessenger astronomy, which is where scientists use light, particles, and space-time ripples called gravitational waves to study different aspects of cosmic events.
In 2017, Swift and other observatories detected light and gravitational waves from the same event, a gamma-ray burst, for the first time. But what astronomers really want is to detect all three messengers from the same event.
As Swift enters its 20th year, it’ll keep watching the ever-changing sky.
Keep up with Swift through NASA Universe on X, Facebook, and Instagram. And make sure to follow us on Tumblr for your regular dose of space!
From observing our moon to Saturn’s mini solar system …here are a few things you should know about our solar system this week:
1. What a Long, Strange—and Revealing—Trip It’s Been
As the Cassini mission builds toward its climactic “Grand Finale,” we’re taking a look back at the epic story of its journey among Saturn’s mini-solar system of rings and moons.
+ Traverse the timeline
2. Our Very Own Moon
Unlike Saturn, Earth has only one moon. Let’s celebrate it! International Observe the Moon Night (InOMN) is a worldwide, public celebration of lunar science and exploration held annually. On Oct. 8, everyone on Earth is invited to observe and learn about the moon together, and to celebrate the cultural and personal connections we all have with it.
+ Join in
3. What’s Up, October?
Even more about Earth’s moon is the subject of this month’s video guide for sky watchers and includes a look at the moon’s phases and when to observe them. Also featured are a guide to upcoming meteor showers and tips on how to catch a glimpse of Saturn.
+ Take a look
4. Nine Lives
Dawn’s discoveries continue, even as the asteroid belt mission marks nine years in space. “For such an overachiever,” writes Dawn’s top scientist, “it’s fitting that now, on its ninth anniversary, the spacecraft is engaged in activities entirely unimagined on its eighth.”
+ Learn more
5. The Incredible Shrinking Mercury
It’s small, it’s hot, and it’s shrinking. Research funded by us suggests that Mercury is contracting even today. This means we now know that Mercury joins Earth as a tectonically active planet.
+ Get the small details
Discover the full list of 10 things to know about our solar system this week HERE.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
“Man must rise above the Earth—to the top of the atmosphere and beyond—for only thus will he fully understand the world in which he lives.” – Socrates
This is an awe-inspiring capture of STS-11/41B rising above the clouds back in 1984.
Our OSIRIS-REx spacecraft will travel to a near-Earth asteroid, called Bennu, where it will collect a sample to bring back to Earth for study.
But why was Bennu chosen as the target destination asteroid for OSIRIS-REx? The science team took into account three criteria: accessibility, size and composition.
Accessibility: We need an asteroid that we can easily travel to, retrieve a sample from and return to Earth, all within a few years time. The closest asteroids are called near-Earth objects and they travel within 1.3 Astronomical Units (AU) of the sun. For those of you who don’t think in astronomical units…one Astronomical Unit is approximately equal to the distance between the sun and the Earth: ~93 million miles.
For a mission like OSIRIS-REx, the most accessible asteroids are somewhere between 0.08 – 1.6 AU. But we also needed to make sure that those asteroids have a similar orbit to Earth. Bennu fit this criteria! Check!
Size: We need an asteroid the right size to perform two critical portions of the mission: operations close to the asteroid and the actual sample collection from the surface of the asteroid. Bennu is roughly spherical and has a rotation period of 4.3 hours, which is in our size criteria. Check!
Composition: Asteroids are categorized by their spectral properties. In the visible and infrared light minerals have unique signatures or colors, much like fingerprints. Scientists use these fingerprints to identify molecules, like organics. For primitive, carbon-rich asteroids like Bennu, materials are preserved from over 4.5 billion years ago! We’re talking about the start of the formation of our solar system here! These primitive materials could contain organic molecules that may be the precursors to life here on Earth, or elsewhere in our solar system.
Thanks to telescopic observations in the visible and the infrared, as well as in radar, Bennu is currently the best understood asteroid not yet visited by a spacecraft.
All of these things make Bennu a fascinating and accessible asteroid for the OSIRIS-REx mission.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
The Gaussian Integral is a beautiful integral for which the area between the e^(-x^2) and the x-axis from negative infinity to positive infinity perfectly equals the square root of pi. Image sources: 1, 2.
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