Elizabeth Howell, Author at Universe Today

December 10, 2013December 23, 2015 by Elizabeth Howell

New Project Aims To Improve Galaxy Simulation — And Help Us Understand More About The Universe

Image of NGC 6872 (left) and companion galaxy IC 4970 (right) locked in a tango as the two galaxies gravitationally interact. The galaxies lie about 200 million light-years away in the direction of the constellation Pavo (the Peacock). Image credit: Sydney Girls High School Astronomy Club, Travis Rector (University of Alaska, Anchorage), Ángel López-Sánchez (Australian Astronomical Observatory/Macquarie University), and the Australian Gemini Office.

Galaxy modelling is complicated, and even more so when different computer models don’t agree on how the factors come together. This makes it hard to understand the nature of our universe. One new project called AGORA (Assembling Galaxies of Resolved Anatomy) aims to resolve the discrepancies and make the results more consistent. Basically, the project aims to compare different codes against each other and also against observations.

“The physics of galaxy formation is extremely complicated, and the range of lengths, masses, and timescales that need to be simulated is immense,” stated Piero Madau, professor of astronomy and astrophysics at the University of California, Santa Cruz and co-chair of the AGORA steering committee.

“You incorporate gravity, solve the equations of hydrodynamics, and include prescriptions for gas cooling, star formation, and energy injection from supernovae into the code. After months of number crunching on a powerful supercomputer, you look at the results and wonder if that is what nature is really doing or if some of the outcomes are actually artifacts of the particular numerical implementation you used.”

This is especially important when it comes to modelling the effect of dark matter on the universe. Since the entity is hard for us to see and therefore to identify, physicists rely on models to make predictions about its effect on galaxies and other forms of more ordinary matter.

Nine codes, nine galaxy formation scenarios: this is the sort of problem that AGORA is devoting itself to resolving by comparing different supercomputer simulations. Credit: Simulations performed by Samuel Leitner (ART-II), Ji-hoon Kim (ENZO), Oliver Hahn (GADGET-2- CFS), Keita Todoroki (GADGET-3), Alexander Hobbs (GADGET-3-CFS and GADGET-3-AFS), Sijing Shen (GASOLINE), Michael Kuhlen (PKDGRAV-2), and Romain Teyssier (RAMSES) — Nine codes, nine galaxy formation scenarios: this is the sort of problem that AGORA is devoting itself to resolving by comparing different supercomputer simulations.
Credit: Simulations performed by Samuel Leitner (ART-II), Ji-hoon Kim (ENZO), Oliver Hahn (GADGET-2- CFS), Keita Todoroki (GADGET-3), Alexander Hobbs (GADGET-3-CFS and GADGET-3-AFS), Sijing Shen (GASOLINE), Michael Kuhlen (PKDGRAV-2), and Romain Teyssier (RAMSES)

“One big challenge, however, has been numerically modeling astrophysical processes over the vast range of size scales in the Universe. Supercomputer simulations are designed with three different size scales relevant to three different phenomena: star formation, galaxy formation, and the large scale structure of the universe,” stated the University of California High-Performance Astrocomputing Center.

This means that models of stars coming to be inside of galaxies have one scale of resolution — enough to look at what the gas and dust is made of, for example — but when looking at the entire universe, the computer is more limited to looking at “simple gravitational interactions of dark matter”, the university added. Of course, the more resolution you can get in a computer model, the better — especially because star formation is affected by processes such as how galaxies interact with surrounding gas.

AGORA’s will first aim to “model a realistic isolated disk galaxy” UCSC states, and then compare the codes used to see what they come up with. You can read more about the project’s aims at this Arxiv pre-print paper (led by the University of California, Santa Cruz’s Ji-hoon Kim) or on the AGORA website.

Sources: University of California Santa Cruz and University of California High-Performance Astrocomputing Center.

December 10, 2013December 23, 2015 by Elizabeth Howell

Level Up! NASA’s Space Station Robot Getting ‘Climbing’ Legs

NASA's Robonaut 2 with "climbing legs" intended to let the robot rove around in the microgravity environment aboard the International Space Station. This version is being tested on the ground for eventual use in space. Credit: NASA

There was much excitement two years ago when the astronauts on space station unpackaged Robonaut 2 (or R2), which is supposed to help with simple tasks. Trouble was, the robot was basically anchored in place and had to be moved around for different tasks. Well, that’s about to change. R2 is getting some “climbing” legs.

After the legs are brought to station and installed — likely sometime early in the new year — Robonaut will be capable of doing tasks both inside and outside (well, outside once a few more unspecified upgrades are finished). This reduces the human risks during spacewalks and frees up the astronauts to do more complicated tasks, NASA said.

“Once the legs are attached to the R2 torso, the robot will have a fully extended leg span of 9 feet, giving it great flexibility for movement around the space station,” NASA stated.

“Each leg has seven joints and a device on what would be the feet called an end effector, which allow the robot to take advantage of handrails and sockets inside and outside the station. A vision system for the end effectors also will be used to verify and eventually automate each limb’s approach and grasp.”

By the way, end effectors were famously used on the Canadarm series of robotic arms that were originally used for grappling satellites. Who knew back in the 1970s that this could be extended to humanoid robots?

Source: NASA

December 10, 2013December 23, 2015 by Elizabeth Howell

How Much Radiation Would You Get During A Mars Mission?

An artist's conception of future Mars astronauts. Credit: NASA/JPL-Caltech

While asking questions about habitability on Mars, one thing that scientists also need to consider is whether it’s safe enough for humans to even do exploration there. Radiation is definitely a big factor — in a press conference yesterday (Dec. 9) for the American Geophysical Union’s conference, scientists said the environment is unlike anything we are used to naturally on Earth.

Radiation on Mars comes from two sources: galactic cosmic rays (over the long term) and solar energetic particles (in short bursts of activity when the sun gets super-active). Of note, the sun has had a muted peak to its solar cycle, so that’s affecting the expected amount of particles on Mars. But the Mars Curiosity rover, in its first 300 Earth days of roaming, has plenty of data on galactic cosmic rays.

On the Martian surface, the average dose is about 0.67 millisieverts (mSv) per day, at least between the measurement period of August 2012 and June 2013. The journey to Mars had a dose of 1.8 mSv per day inside the spaceship. So what does that means for NASA’s human health consideration concerns?

NASA's Mars rover Curiosity took this self-portrait, composed of more than 50 images using its robotic arm-mounted MAHLI camera, on Feb. 3. The image shows Curiosity at the John Klein drill site. A drill hole is visible at bottom left. Credit: NASA / JPL / MSSS / Marco Di Lorenzo / Ken Kremer- kenkremer.com — NASA’s Mars rover Curiosity took this self-portrait, composed of more than 50 images using its robotic arm-mounted MAHLI camera, on Feb. 3. The image shows Curiosity at the John Klein drill site. A drill hole is visible at bottom left. Credit: NASA / JPL / MSSS / Marco Di Lorenzo / Ken Kremer- kenkremer.com

With a 500-day trip on the surface and the journey to and from Mars (which would take 180 days each way), NASA is saying the total dosage for the mission would be about 1 Sv. Population studies over the long term have shown that increases the fatal cancer risk by 5%. Current NASA guidelines for low-Earth orbit don’t allow for a more than 3% increase, but 1 Sv is within the guidelines for several other space agencies.

But don’t rule out the trip to Mars yet, NASA states: “[NASA] does not currently have a limit for deep space missions, and is working with the National Academies Institute of Medicine to determine appropriate limits for deep space missions, such as a mission to Mars in the 2030s.”

Besides, other entities are thinking about going, such as Mars One.

Read more about the radiation findings in this Dec. 9 article on Science. The research was led by Don Hassler, a Southwest Research Institute program director and principal investigator of Curiosity’s radiation assessment detector (RAD).

Source: Southwest Research Institute

December 9, 2013April 26, 2016 by Elizabeth Howell

‘Glowing Wreck Of A Star’ Reveals Cosmic Cannibalism

Composite image of Circinus X-1, which is about 24,000 light-years from Earth in the constellation Circinus. Credit: X-ray: NASA/CXC/Univ. of Wisconsin-Madison/S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA

Circinus X-1 may look like a serene place from a distance, but in reality this gassy nebula is quite a busy spot. Embedded in the nebula is the neutron star that is also a leftover of the supernova that produced the gas. Not only that, but the neutron star is still locked on to a companion and is in fact “cannibalizing” it, astronomers said.

The “glowing wreck of a star”, as the team called it, is exciting because it demonstrates what systems look like in the first stages after an explosion. The nebula is an infant in cosmic terms, with an upper limit to its age of just 4,500 years. To put that in human terms, that’s around the time of the first civilizations (such as in Mesopotamia).

“The fact that we have this remnant along with the neutron star and its companion means we can test all kinds of things,” stated Sebastian Heinz, an astronomy professor at the University of Wisconsin-Madison who led the research.

“Our observations solve a number of puzzles both about this object and the way that neutron stars evolve after they are born. For example, the unusual elliptical orbit on which these two stars swing around each other is exactly what you would expect for a very young X-ray binary.”

X-ray binaries are typically made up of a black hole or a neutron star that is locked on to a “normal” companion star such as that of our sun. That star won’t stay normal forever, however, as it’s being subject to very intense gravity from the black hole or neutron star. Its starstuff is being pulled off, heated, and then emitting radiation in X-rays that are easily trackable across the universe.

While X-ray binaries have been spotted before, seeing one along with a nebula is something special. By comparison, the gas cloud doesn’t stick around for very long — just 100,000 years or so — while the stars can be there for a while longer.

Checking out this star system could not only teach scientists about stellar evolution, but about the nature of neutron stars. One thing puzzling the team right now is why the neutron star has a faint magnetic field, which stands against established theory. Further study will be required to figure out why it isn’t as strong as expected.

Combining observations done with ESO's Very Large Telescope and NASA's Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. The black hole blows a huge bubble of hot gas, 1,000 light-years across or twice as large and tens of times more powerful than the other such microquasars. The stellar black hole belongs to a binary system as pictured in this artist's impression. Credit: ESO/L. Calçada — A binary X-ray system with a black hole (right) and companion star. Credit: ESO/L. Calçada

This high-resolution view from NASA’s Chandra X-Ray Telescope and the Australia Telescope Compact Array, however, has revealed some new things.

“I have been perplexed by the unusually strong evolution of the orbit of Circinus X-1 since my graduate-school days,” stated Niel Brandt, an astronomer at Pennsylvania State University who is on the team. “The discovery now of this system’s youth provides a satisfying explanation for why its orbit evolves so strongly — because the system likely still is settling down after its violent birth.”

You can read more in the Dec. 4 publication in The Astrophysical Journal or, in prepublished form, on Arxiv.

Sources: University of Wisconsin-Madison and Pennsylvania State University

December 9, 2013December 23, 2015 by Elizabeth Howell

This Spooky X-Ray ‘Hand’ Demonstrates A Pulsar Star Mystery

This X-ray nebula appears to look like a human hand. The ghostly shape comes courtesy of a pulsar star called PSR B1509-58 (B1509 for short) that is just 12 miles or 19 kilometers in diameter. The nebula itself is 150 light-years across. Image taken by NASA's Chandra X-ray Observatory. Credit: NASA/CXC/CfA/P. Slane et al.

That spooky hand in the image above is producing questions for scientists. While the shape only coincidentally looks like a human hand, scientists are still trying to figure out how a small star produced such a large shape visible in X-rays.

Pulsar star PSR B1509-58 (or B1509 for short) is a 12-mile (19-kilometer) remnant of a much larger star that exploded and left behind a quickly spinning neutron star. Energy leaves mostly via neutrino (or neutral particle) emission, with a bit more coming out via beta decay, or a radioactive process where charged particles leave from atoms.

Using a new model, scientists found that so much energy comes out from neutrino emission that there shouldn’t be enough left for the beta decay to set off the X-rays you see here in this image, or in other situations. Yet it’s still happening. And that’s why they’re hoping to take a closer look at the situation.

Artist's conception of a neutron star flare. Credit: University of California Santa Cruz — Artist’s conception of a neutron star flare. Credit: University of California Santa Cruz

“Scientists are intrigued by what exactly powers these massive explosions, and understanding this would yield important insights about the fundamental forces in nature, especially on the astronomical/cosmological scale,” stated Peter Moller, who is with the theoretical division of Los Alamos National Laboratory and participated in the research.

Preliminary studies indicate that to better understand what’s happening on the surface of these objects, computer models must endeavor to “describe the shape of each individual nuclide” (or atom that has a certain number of protons and neutrons in its nucleus). That’s because not all of these nuclides are simple spheres.

Using facilities at Los Alamos, scientists created databases with different types of nuclides that had various beta-decay properties. They then plugged this into a Michigan State University model of neutron stars to see what energy was released as the stars accrete or come together.

Accretion can cause neutron stars to flare violently

The results stood against what was a “common assumption”, the scientists stated, that the radioactive action would be enough to power the X-rays. They urge more study on this front, especially using a proposed Facility for Rare Isotope Beams that would be built at Michigan State, using funding from the U.S. Department of Energy Office of Science. FRIB project participants are hoping that will be ready in the 2020s.

You can read more about the research in the Dec. 1 edition of Nature. It was led by Hendrik Schatz, a professor at the National Superconducting Cyclotron Laboratory at Michigan State.

Source: Los Alamos National Laboratory

December 6, 2013December 23, 2015 by Elizabeth Howell

Zot! Curiosity Punches Laser Hole No. 100,000 On Mars

This mosaic shows a rock, nicknamed "Ithaca" examined by the NASA Curiosity rover's Chemistry and Camera (ChemCam) laser. The 100,000th laser shot of Curiosity's mission is marked in the image. The shot took place on Oct. 30, 2013 and was announced in early December. Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/UNM

The reports are in: it appears that Earth has the upper hand in firing laser shots on Mars. More seriously, however, the Curiosity rover has surpassed the uber-cool milestone of shooting 100,000 holes in the Red Planet’s surface to learn more about its chemical composition.

As you can see in the picture, the 100,000th shot took place on a rock nicknamed “Ithaca” on Oct. 30 from a distance of 13 feet, 3 inches (4.04 meters) away. (The news was just announced recently; as of early December, the laser had fired more than 102,000 times).

“The Chemistry and Camera instrument (ChemCam) uses the infrared laser to excite material in a pinhead-size spot on the target into a glowing, ionized gas, called plasma. ChemCam observes that spark with the telescope and analyzes the spectrum of light to identify elements in the target,” NASA stated.

December 6, 2013December 23, 2015 by Elizabeth Howell

This Exoplanet Is Turning Planetary Formation Scenarios Upside Down

Artist's conception of a planet like HD106906 b. Visible in the picture is a debris disk and its distant host star. Credit: NASA/JPL-Caltech

What the heck is that giant exoplanet doing so far away from its star? Astronomers are still trying to figure out the curious case of HD 106906 b, a newly found gas giant that orbits at an astounding 650 astronomical units or Earth-sun distances from its host star. For comparison, that’s more than 20 times farther from its star than Neptune is from the sun.

“This system is especially fascinating because no model of either planet or star formation fully explains what we see,” stated Vanessa Bailey, a graduate astronomy student at the University of Arizona who led the research.

HD 106906 b is 11 times the size of Jupiter, throwing conventional planetary formation theory for a loop. Astronomers believe that planets gradually form from clumps of gas and dust that circle around young stars, but that process would take too long for this exoplanet to form — the system is just 13 million years old. (Our own planetary system is about 4.5 billion years old, by comparison.)

The discovery image of HD 106906 b, shown in thermal infrared light from instruments on the Magellan telescope at the European Southern Observatory in Chile. The image has been changed to take out light from its very bright host star. The planet orbits more than 20 times farther from its host star than Neptune does from the sun. (AU = astronomical units, or Earth-sun distances). Credit: Vanessa Bailey

Another theory is that if the disc collapses quickly, perhaps it could spawn a huge planet — but it’s improbable that there is enough mass in the system for that to happen. Perhaps, the team says, this system is like a “mini binary star system”, with HD 106906 b being more or less a failed star of some sort. Yet there is at least one problem with that theory as well; the mass ratio of the planet and star is something like 1 to 100, and usually these scenarios occur in ratios of 1 to 10 or less.

“A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit,” Bailey stated.

“It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet’s progenitor clump was starved for material and never grew large enough to ignite and become a star.”

Young binarys stars: Image credit: NASA — Young binary stars: Image credit: NASA

Besides puzzling out how HD 106906 b came to be, astronomers are also interested in the system because they can clearly see leftovers or a debris disk from the system’s formation. By studying this system further, astronomers hope to figure out more about how young planets evolve.

At 2,700 degrees Fahrenheit (1,500 degrees Celsius), the planet is most easily visible in infrared. The heat is from when the planet was first coalescing, astronomers said.

The astronomers spotted the planet using the Magellan telescope at the European Southern Observatory’s Atacama Desert in Chile. It was visible in both the Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera on the telescope. The planet was confirmed using Hubble Space Telescope images from eight years ago, as well as the FIRE spectrograph on Magellan that revealed more about the planet’s “nature and composition”, a press release stated.

The research paper is now available on the prepublishing site Arxiv and will be published in a future issue of Astrophysical Journal Letters.

Source: University of Arizona

December 5, 2013December 23, 2015 by Elizabeth Howell

Could Particle ‘Spooky Action’ Define The Nature Of Gravity?

Diagram of a wormhole, or theoretical shortcut path between two locations in the universe. Credit: Wikipedia

Quantum physics is a fascinating yet complicated subject to understand, and one of the things that freaks out physics students every is the concept of entanglement. That occurs when physicists attempt to measure the state of a particle and that affects the state of another particle instantly. (In reality, the particles are in multiple states — spinning in multiple directions, for example — and can only be said to be in one state or another when they are measured.)

“Spooky action at a distance” is how Albert Einstein reportedly referred to it. Here’s the new bit about this: Julian Sonner, a senior postdoctoral researcher at the Massachusetts Institute of Technology, led research showing that when two of these quarks are created, string theory creates a wormhole linking the quarks.

According to MIT, this could help researchers better understand the link between gravity (which takes place on a large scale) to quantum mechanics (which takes place on a very tiny scale). As MIT puts it, up to now it’s been very hard for physicists to “explain gravity in quantum-mechanical terms”, giving rise to a preoccupation of coming up with a single unifying theory for the universe. No luck yet, but many people believe it exists.

The a-theorem could help to explain the theory that describes quarks, fundamental particles seen here in a three-dimensional computer-generated simulation. PASIEKA/SPL — Quarks, fundamental particles seen here in a three-dimensional computer-generated simulation. PASIEKA/SPL

“There are some hard questions of quantum gravity we still don’t understand, and we’ve been banging our heads against these problems for a long time,” Sonner stated. “We need to find the right inroads to understanding these questions.”

Quantum entanglement sounds so foreign to our experience because it appears to exceed the speed of light, which violates Einstein’s general relativity. (The speed limit is still being tested, of course, which is why scientists were so excited when it appeared particles were moving faster than light in a 2011 experiment that was later debunked due to a faulty sensor.)

Anyway, this is how the new research proceeded:

– Sonner examined the work of Juan Maldacena of the Institute for Advanced Study and Leonard Susskind of Stanford University. The physicists were looking at how entangled black holes would behave. “When the black holes were entangled, then pulled apart, the theorists found that what emerged was a wormhole — a tunnel through space-time that is thought to be held together by gravity. The idea seemed to suggest that, in the case of wormholes, gravity emerges from the more fundamental phenomenon of entangled black holes,” MIT stated.

Two nascent black holes formed by the collapse of an early supergiant star. From a visualization by by Christian Reisswig (Caltech).

– Sonner then set about to create quarks to see if he could watch what happens when two are entangled with each other. Using an electric field, he was able to catch pairs of particles coming out of a vacuum environment with a few “transient” particles in it.

– Once he caught the particles, he mapped them in terms of space-time (four-dimensional space). Note: gravity is believed to be the fifth dimension because it can bend space-time, as you can see in these images of galaxies below.

– Sonner then tried to figure out what would happen in the fifth dimension when quarks were entangled in the fourth dimension, using a string theory concept called holographic duality. “While a hologram is a two-dimensional object, it contains all the information necessary to represent a three-dimensional view. Essentially, holographic duality is a way to derive a more complex dimension from the next lowest dimension,” MIT stated.

The HST WFPC2 image of gravitational lensing in the galaxy cluster Abell 2218, indicating the presence of large amount of dark matter (credit Andrew Fruchter at STScI).

– And it was under holographic duality that Sonner found a wormhole would be created. The implication is that gravity itself may come out of entanglement of these particles, and that the bending we see in the universe would also be due to the entanglement.

“It’s the most basic representation yet that we have where entanglement gives rise to some sort of geometry,” Sonner stated. “What happens if some of this entanglement is lost, and what happens to the geometry? There are many roads that can be pursued, and in that sense, this work can turn out to be very helpful.”

You can view the research in Physical Review Letters.

Source: Massachusetts Institute of Technology

December 5, 2013December 23, 2015 by Elizabeth Howell

Saturn’s Mysterious Hexagon Behaves Like Earth’s Ozone Hole

At Saturn, NASA's Cassini spacecraft snapped pictures showing a high-resolution view of a hexagon-shaped jet stream. Credit: NASA/JPL-Caltech/SSI/Hampton

A raging hurricane is creating a “suck zone” at Saturn’s north pole. The handy Cassini spacecraft recently captured a bunch of images of the six-sided jet stream surrounding the storm, which mission managers then put together into an awesome animation showing the wind currents shifting. (You can see the animation below the jump.)

The feature is pretty in a picture, but NASA has a special interest because there is nothing else like this anywhere in our solar system, the agency stated. The immense storm stretches 20,000 miles (30,000 kilometers) across with winds whipping in its jet stream at 200 miles per hour (322 kilometers per hour). And despite all the turbulence, the storm is staying put at the north pole for reasons scientists are still trying to understand.

“The hexagon is just a current of air, and weather features out there that share similarities to this are notoriously turbulent and unstable,” said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “A hurricane on Earth typically lasts a week, but this has been here for decades — and who knows — maybe centuries.”

An animation of Cassini Saturn images showing a hexagonal jet stream surrounding a storm at the north pole. Credit: NASA/JPL-Caltech/SSI/Hampton University

Cassini has been orbiting Saturn since 2004, but it’s only since last year that it’s been able to peer at the hexagon with much success. That’s because the angle of the sun is finally favorable to peer at the storm. This has allowed scientists, for example, to look at the types of particles inside. They discovered that the jet stream is a sort of barrier around the storm, delineating a location with a lot of small haze particles and few large haze particles. (It’s the opposite outside of the jet stream). Scientists said it looks like the Antarctic ozone hole on Earth.

“The Antarctic ozone hole forms within a region enclosed by a jet stream with similarities to the hexagon,” NASA stated.

“Wintertime conditions enable ozone-destroying chemical processes to occur, and the jet stream prevents a resupply of ozone from the outside. At Saturn, large aerosols cannot cross into the hexagonal jet stream from outside, and large aerosol particles are created when sunlight shines on the atmosphere. Only recently, with the start of Saturn’s northern spring in August 2009, did sunlight begin bathing the planet’s northern hemisphere.”

Should Cassini have enough funding to function for a few more years, scientists are eager to watch as Saturn gets to its summer solstice in 2017 and the lighting gets even better around the north pole.

NASA also held an interesting Google+ Hangout yesterday (Nov. 4) about Saturn and the Cassini mission that featured Carolyn Porco, director of the Cassini Imaging Team and the Cassini Imaging Central Laboratory for Operations (CICLOPS). The whole video below is worth a watch, but here’s a little tidbit to let you know some of what was talked about:

“If you took all the mass of Saturn’s rings and recomposed it into a moon, it would be no bigger than Enceladus, so it’s a big spectacle coming from little mass,” Porco said. “The main rings are very thin, only about 30 feet [9 meters] thick, no bigger than about 2 stories in a modern day building. Despite the fact they are about 280,000 km [174,000 miles] across.”

December 5, 2013December 23, 2015 by Elizabeth Howell

How Do We Learn About An Alien Planet’s Size And Atmosphere?

More than 1,000 exoplanets have been confirmed and cataloged (PHL @ UPR Arecibo)

The fun and challenge of exoplanet science is the planets are so far away and so tiny. Figuring out what they look like isn’t as simple as just pointing a telescope and observing. This new video from NASA explains how astronomers use the parent star to figure out the planet’s size, mass, atmosphere and more.

Alien planets are generally detected through blocking the light of their parent star (from the vantage point of Earth) or through their gravitational effects that cause the star to slightly “wobble” during each orbit. These methods can reveal the mass and size of the planet. As for the atmosphere, that takes a bit more work.

“As the planet crosses its star, its atmosphere absorbs certain wavelengths of light or colors, while allowing other wavelengths of light to pass through,” the video stated.

“Because each molecule absorbs distinct wavelengths, astronomers spread the light into its spectrum of colors to see which wavelengths have been absorbed. The dark absorption bands act as molecular fingerprints, revealing the atmosphere’s chemical makeup.”

And this science can reveal amazing things, such as the recent Hubble find of a “clear signal” of water in five exoplanet atmospheres. The video has more detail on how individual elements are identified, so be sure to check it out.