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.
This article was originally published on Aug 10, 2012. We’ve updated it and added this cool new video!
Sending spacecraft to Mars is all about precision. It’s about blasting off from Earth with a controlled explosion, launching a robot into space in the direction of the Red Planet, navigating the intervening distance between our two planets, and landing with incredible precision.
This intricate and complicated maneuver means knowing the exact distance from Earth to Mars. Since Mars and Earth both orbit the Sun – but at different distance, with different eccentricities, and with different orbital velocities – the distance between then is constantly changing
The first person to ever calculate the distance to Mars was the astronomer Giovanni Cassini, famous for his observations of Saturn. Giovanni made observations of Mars in 1672 from Paris, while his colleague, Jean Richer made the same observation from Cayenne, French Guiana. They used the parallax method to calculate the distance to Mars with surprising accuracy.
Every two years, the Earth passes Mars as they orbit around the Sun, which causes it to appear like it is slowing down and moving in reverse in the sky (aka. “retrograde motion”). Credit: Tunç Tezel
However, astronomers now calculate the distance to objects in the Solar System using the speed of light. They measure the time it takes for signals to reach spacecraft orbiting other planets. They can bounce powerful radar off planets and measure the time it takes for signals to return. This allows them to measure the distance to planets, like Mars, with incredible accuracy.
Distance Between Earth and Mars:
So, how far away is Mars? The answer to that question changes from moment to moment because Earth and Mars are orbiting the Sun. It also requires a little explanation about the orbital mechanics of each. Both Earth and Mars are following elliptical orbits around the Sun, like two cars travelling at different speeds on two different racetracks.
Sometimes the planets are close together, and other times they’re on opposite sides of the Sun. And although they get close and far apart, those points depend on where the planets are on their particular orbits. So, the Earth Mars distance is changing from minute to minute.
The planets don’t follow circular orbits around the Sun, they’re actually traveling in ellipses. Sometimes they’re at the closest point to the Sun (called perihelion), and other times they’re at the furthest point from the Sun (known as aphelion).
Mars axial tilt and eccentricity as it orbits around the Sun. Credit and copyright: Encyclopedia Britannica
To get the closest point between Earth and Mars, you need to imagine a situation where Earth and Mars are located on the same side of the Sun. Furthermore, you want a situation where Earth is at aphelion, at its most distant point from the Sun, and Mars is at perihelion, the closest point to the Sun.
Earth and Mars Opposition:
When Earth and Mars reach their closest point, this is known as opposition. It’s the time that Mars appears as a bright red star of the sky; one of the brightest objects, rivaling the brightness of Venus or Jupiter. There’s no question Mars is bright and close, you can see it with your own eyes. And theoretically at this point, Mars and Earth will be only 54.6 million kilometers from each other.
But here’s the thing, this is just theoretical, since the two planets haven’t been this close to one another in recorded history. The last known closest approach was back in 2003, when Earth and Mars were only 56 million km (or 33.9 million miles) apart. And this was the closest they’d been in 50,000 years.
Opposition occurs when Mars and Earth line up on the same side of the Sun. The two planets are closest together at that time. Credit: Bob King
Here’s a list of Mars Oppositions from 2007-2020 (source)
Dec. 24, 2007 – 88.2 million km (54.8 million miles)
Jan. 29, 2010 – 99.3 million km (61.7 million miles)
Mar. 03, 2012 – 100.7 million km (62.6 million miles)
Apr. 08, 2014 – 92.4 million km (57.4 million miles)
May. 22, 2016 – 75.3 million km (46.8 million miles)
Jul. 27. 2018 – 57.6 million km (35.8 million miles)
Oct. 13, 2020 – 62.1 million km (38.6 million miles)
2018 should be a very good year, with a Mars looking particularly bright and red in the sky.
Earth and Mars Conjunction:
On the opposite end of the scale, Mars and Earth can be 401 million km apart (249 million miles) when they are in opposition and both are at aphelion. The average distance between the two is 225 million km. When Mars and Earth are at their closest, you have your launch window.
Since 1995, Mars has been at such an “opposition” with the Sun seven times. A color composite from each of the seven Hubble opposition observations has been assembled in this mosaic to showcase the beauty and splendor that is The Red Planet. Credit: NASA/ESA
Mars and Earth reach this closest point to one another approximately every two years. And this is the perfect time to launch a mission to the Red Planet. If you look back at the history of launches to Mars, you’ll notice they tend to launch about every two years.
Here’s an example of recent Missions to Mars, and the years they launched:
MER-A Spirit – 2003
MER-B Opportunity – 2003
Mars Reconnaissance Orbiter – 2005
Phoenix – 2007
Fobos-Grunt – 2011
MSL Curiosity – 2011
See the trend? Every two years. They’re launching spacecraft when Earth and Mars reach their closest point.
Spacecraft don’t launch directly at Mars; that would use up too much fuel. Instead, spacecraft launch towards the point that Mars is going to be in the future. They start at Earth’s orbit, and then raise their orbit until they intersect the orbit of Mars; right when Mars is at that point. The spacecraft can then land on Mars or go into orbit around it. This journey takes about 250 days.
Communicating with Mars:
With these incredible distances between Earth and Mars, scientists can’t communicate with their spacecraft in real time. Instead, they need to wait for the amount of time it takes for transmissions to travel from Earth to Mars and back again.
Artist’s impression of the Spirit Rover. One of two rovers that were part of MER program, the other was Opportunity, that began communicating back information that have helped NASA scientists characterize the Martian environment and geological history. NASA/JPL-Caltech
When Earth and Mars are at their theoretically closest point of 54.6 million km, it would take a signal from Earth about 3 minutes to make the journey, and then another 3 minutes for the signals to get back to Earth. But when they’re at their most distant point, it takes more like 21 minutes to send a signal to Mars, and then another 21 minutes to receive a return message.
This is why the spacecraft sent to Mars are highly autonomous. They have computer systems on board that allow them to study their environment and avoid dangerous obstacles completely automatically, without human intervention.
The distance from Earth to Mars is the main reason that there has never been a manned flight to the Red Planet. Scientists around the world are working on ways to shorten the trip with the goal of sending a human into Martian orbit within the next decade.
For more information, this website lists every Mars opposition time, from recent past all the way in the far future. You can also use NASA’s Solar System Simulator to see the current position of any object in the Solar System.
Ignition of Next Generation SpaceX Falcon 9 rocket on Dec. 3, 2013 from Launch Complex 40 at Cape Canaveral Air Force Station, FL lofting SES-8 telecommunications satellite to geosynchronous orbit. Credit: Alan Walters/americaspace.com
CAPE CANAVERAL AIR FORCE STATION, FL – The flawless blastoff of SpaceX’s next generation Falcon 9 rocket on Tuesday Dec. 3 put on a spectacular sky show along the Florida Space Coast that was both beautiful and unforgettable – besides being truly historic as the firms first ever delivery of a commercial space satellite to the lucrative market of geostationary orbit.
For your enjoyment here’s a collection of photos and videos from fellow space photojournalists of the 5:41 p.m. EST sunset launch from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, FL.
Following a pair of launch scrubs last week on Nov. 25 and Thanksgiving Day Nov. 28 caused by issues with the powerful new Merlin 1-D first stage engines, the third time was fat last the charm as the Falcon 9 blasted precisely at the opening of the 86 minute launch window.
A SpaceX Falcon 9 V1.1 rocket vents oxygen following Thursday evenings first launch attempt from Launch Complex 40 at Cape Canaveral Air Force Station. The first attempt was halted after computers showed that the engines had a slower than expected thrust rate upon startup. Credit: Walter Scriptunas II imagesAs the Falcon 9 begins to ‘thread the needle’ of the lightning wires, a shower of ice and flames and steam scatters, cascades and billows. Credit: nasatech.netClear of the catenary lightning wires, the Falcon 9/SES-8 mission streaks to orbit. Credit: nasatech.netBeautiful streak shot of SpaceX Falcon 9 rocket launch with SES-8 satellite on Dec. 3, 2013. Credit: John StudwellSpaceX Falcon 9 rocket with SES-8 communications satellite soars to orbit. Credit: Ken Kremer/kenkremer.comFalcon 9/SES-8 streak to orbit on Dec. 3, 2013. Credit: Jeff SeibertFalcon 9/SES-8 streak to orbit on Dec. 3, 2013. Credit: Jeff SeibertWispy exhaust plume from SpaceX Falcon 9 rocket launch with SES-8 satellite on Dec. 3, 2013. Credit: John StudwellBlastoff of Falcon 9/SES-8 satellite on Dec. 3, 2013. Credit: Julian Leek
Launch Video
Stay tuned here for continuing SpaceX & MAVEN news and Ken’s SpaceX and MAVEN launch reports from on site at Cape Canaveral & the Kennedy Space Center press site.
If you live in the southern hemisphere, the southern sky constellation of Centaurus may look a little different to you tonight, as a bright nova has been identified in the region early this week.
An animation showing a comparison between the constellation Centaurus before and after a nova eruption. Credit and copyright: Ernesto Guido, Nick Howes and Martino Nicolini/Remanzacco Observatory. Click for larger version.
The initial discovery of Nova Centauri 2013 (Nova Cen 2013) was made by observer John Seach based out of Chatsworth Island in New South Wales Australia. The preliminary discovery magnitude for Nova Cen 2013 was magnitude +5.5, just above naked eye visibility from a good dark sky site. Estimates by observers over the past 24 hours place Nova Cen 2013 between magnitudes +4 and +5 “with a bullet,” meaning this one may get brighter still as the week progresses.
Nova Cen 2013 as imaged from the Siding Spring observatory on December 3rd. (Credit: Ernesto Guido, Nick Howes & Martino Nicolini/Remanzacco Observatory).
We first got wind of the discovery via the American Association of Variable Star Observers yesterday afternoon when alert notice 492 was issued. Established in 1911, the AAVSO is a great resource for info and a fine example of amateur collaboration in the effort to conduct real scientific observation.
Follow-up spectra measurements by Rob Kaufman in White Cliffs Australia and Malcolm Locke in Christchurch New Zealand demonstrated the presence of strong hydrogen alpha and hydrogen beta emission lines, the classic hallmark of an erupting nova. Like Nova Delphini 2013 witnessed by observers in the northern hemisphere, this is a garden variety nova located in our own galaxy, going off as seen along the galactic plane from our Earthbound perspective. A handful of galactic novae are seen each year, but such a stellar conflagration reaching naked eye visibility is worthy of note. In fact, Nova Cen 2013 is already knocking on the ranks of the 30 brightest novae observed of all time.
A narrow field image (inverted B/W) of Nova Cen 2013. (Credit: Ednilson Oliveira).
This is not to be confused with a supernova, the last of which observed in our galaxy was Kepler’s Supernova in 1604, just before the advent of the telescope in modern astronomy. Supernovae are seen in other galaxies all the time, but here at home, you could say we’re “due”.
So, who can see Nova Cen 2013, and who’s left out? Well, the coordinates for the nova are:
Right Ascension: 13 Hours 54’ 45”
Declination: -59°S 09’ 04”
That puts it deep in the southern celestial hemisphere sky where the constellation Centaurus meets up with the constellations of Circinus, Musca and the Crux. Located within three degrees of the +0.6th magnitude star Hadar — also named Beta Centauri — it would be possible to capture the southern deep sky objects of the Coal Sack and Omega Centauri with Nova Cen 2013 in the same wide field of view.
The field of view of Nova Centauri 2013 with a five degree Telrad “bullseye” added for scale. Note that magnitude for selected comparison stars are quoted, minus the decimal points. (Created using Stellarium).
Though Nova Cen 2013 technically peeks above the southern horizon from the extreme southern United States, the viewing circumstances aren’t great. In fact, the nova only rises just before the Sun as seen from Miami in December, at 25 degrees north latitude. The Centaurus region is much better placed in northern hemisphere during the springtime, when many southern tier states can actually glimpse the celestial jewels that lie south, such as Omega Centauri.
But the situation gets better, the farther south you go. From Guayaquil, Ecuador just below the equator, the nova rises to the southeast at about 3 AM local, and sits 20 degrees above the horizon at sunrise.
11PM local, from latitude 40 degrees south looking to the southeast. (Created by the author using Starry Night Education Software).
The nova will be circumpolar for observers south of -30 degrees latitude, including cities of Buenos Aires, Cape Town, Sydney and Auckland. Remember, its springtime currently in the southern hemisphere, as we head towards the solstice on December 21st and the start of southern hemisphere summer. We’ve been south of the equator about a half dozen times and it’s a unique experience – for northern star gazers, at least – to see familiar northern constellations such as Orion and Leo hang “upside down” as strange a wonderful new constellations beckon the eye to the south. Also, though the Sun still rises to the east, it transits to the north as you get deep into the southern hemisphere, a fun effect to note!
Latitudes, such as those on par with New Zealand, will get the best views of Nova Cen 2013. Based near latitude 40 degrees south, observers will see the nova about 10 degrees above the southern horizon at lower culmination at a few hour after sunset, headed towards 40 degrees above the southeastern horizon at sunrise.
All indications are that Nova Cen 2013 is a classical nova, a white dwarf star accreting matter from a binary companion until a new round of nuclear fusion occurs. Recurrent novae such as T Pyxidis or U Scorpii may erupt erratically in this fashion over the span of decades.
As of yet, there is no firm distance measurement for Nova Cen 2013, though radio observations with southern sky assets may pin it down. One northern hemisphere based program, known as the EVLA Nova Project, seeks to do just that.
Congrats to John Seach on his discovery, and if you find yourself under southern skies, be sure to check out this astrophysical wonder!
Got pics of Nova Centauri 2013? Be sure to send ‘em in to Universe Today!
Artist's conception of two black holes gravitationally bound to each other. Credit: NASA
Two black holes in the middle of a galaxy are gravitationally bound to each other and may be starting to merge, according to a new study.
Astronomers came to that conclusion after studying puzzling behavior in what is known as WISE J233237.05-505643.5, a discovery that came from NASA’s Wide-field Infrared Survey Explorer (WISE). Follow-up studies came from the Australian Telescope Compact Array and the Gemini South telescope in Chile.
“We think the jet of one black hole is being wiggled by the other, like a dance with ribbons,” stated research leader Chao-Wei Tsai of NASA’s Jet Propulsion Laboratory. “If so, it is likely the two black holes are fairly close and gravitationally entwined.”
“The dance of these black hole duos starts out slowly, with the objects circling each other at a distance of about a few thousand light-years,’ NASA added in a press release. “So far, only a few handfuls of supermassive black holes have been conclusively identified in this early phase of merging. As the black holes continue to spiral in toward each other, they get closer, separated by just a few light-years. ”
JPL’s venerable Ed Stone, the Project Scientist for the Voyager spacecraft for over 40 years, made an appearance on the Colbert Report last night, bantering easily with the no-holds-barred host and discussing the significance of the Voyager mission, from the two launches in 1977 to Voyager 1’s recent celebrated arrival in interstellar space.
Colbert also was tasked by NASA to present Stone with NASA’s Distinguished Public Service Medal for a lifetime of scientific achievement. See below:
Artist's conception of NASA’s Van Allen Probes twin spacecraft. Credit: Andy Kale, University of Alberta
The radiation-heavy Van Allen Belts around Earth contain particles that can move at almost the speed of light across vast distances, new research reveals. The information came from an instrument flown aboard the Van Allen Probes twin NASA spacecraft, which launched in 2012.
According to scientists, the process that creates this is similar to what happens in the Large Hadron Collider and other particle accelerators. The magnetic field on the Earth accelerates electrons faster as these particles orbit the planet. While scientists had spotted this process happening at small scales before, the new paper has seen this across hundreds of thousands of kilometers or miles.
“With the Van Allen Probes, I like to think there’s no place for these particles to hide because each spacecraft is spinning and ‘glimpses’ the entire sky with its detector ‘eyes’, so we’re essentially getting a 360-degree view in terms of direction, position, energy, and time,” stated Harlan Spence, principal scientist for the Energetic Particle, Composition, and Thermal Plasma (ECT) instrument aboard the probes, and co-author on the research paper. He is also director of the University of New Hampshire Institute for the Study of Earth, Oceans, and Space.
The research was led by University of Alberta physicist Ian Mann, and is available in Nature Communications. “People have considered that this acceleration process might be present but we haven’t been able to see it clearly until the Van Allen Probes,” Mann stated.
Artist's conception of the Dawn spacecraft approaching the asteroid Ceres. Credit: NASA/JPL-Caltech
The next few years will be banner ones for learning about dwarf planets. While the high-profile New Horizons spacecraft zooms towards a Pluto date in 2015, the Dawn spacecraft is making a more stealthy (in terms of media coverage) run at Ceres, which is the smallest and closest dwarf planet to Earth.
The Dawn spacecraft, as readers likely recall, made its first port of call at fellow protoplanet Vesta. What excites scientists this time around is the likelihood of water ice on Ceres’ surface. Vesta, by contrast, was very dry.
Here’s Dawn’s agenda once it gets to Ceres in April 2015:
“Dawn will make its first full characterization of Ceres later in April, at an altitude of about 8,400 miles (13,500 kilometers) above the icy surface. Then, it will spiral down to an altitude of about 2,750 miles (4,430 kilometers), and obtain more science data in its survey science orbit. This phase will last for 22 days, and is designed to obtain a global view of Ceres with Dawn’s framing camera, and global maps with the visible and infrared mapping spectrometer (VIR),” NASA stated.
“Dawn will then continue to spiral its way down to an altitude of about 920 miles (1,480 kilometers), and in August 2015 will begin a two-month phase known as the high-altitude mapping orbit. During this phase, the spacecraft will continue to acquire near-global maps with the VIR and framing camera at higher resolution than in the survey phase. The spacecraft will also image in ‘stereo’ to resolve the surface in 3-D.”
Dawn will then zoom down to an altitude of just 233 miles (375 kilometers) in November 2015 for three months to obtain information about elements and the dwarf planet’s gravity. Dawn will use its Gamma Ray and Neutron Detector (GRaND) to do the first part and a gravity experiment to perform the second.
Ceres. Image credit: NASA
To conserve fuel, Dawn will also use a “hybrid” pointing control method to keep it on track, using both reaction wheels and thrusters to stay in the right direction. This is needed because two of its four reaction wheels had “developed excessive friction” by the time Dawn departed Vesta. The hybrid method was tested for 27 hours and successfully concluded Nov. 13. You can check out more about the hybrid mode at this link.
SpaceX is suing the Air Force for the right to compete for US national security satellites launches using Falcon 9 rockets such as this one which successfully launched the SES-8 communications satellite on Dec. 3, 2013 from Pad 40 at Cape Canaveral, FL. Credit: Ken Kremer/kenkremer.com
CAPE CANAVERAL AIR FORCE STATION, FL – SpaceX scored a spectacular launch success this evening (Dec. 3 ) when the maiden flight of their upgraded Falcon 9 rocket from Florida scorched the sky of the Florida Space Coast and successfully delivered a commercial space satellite to geostationary orbit for the first time ever – thereby revolutionizing the commercial space industry from this day forward.
The third time was finally the charm as the Falcon 9 blasted off precisely on time at 5:41 p.m. EST from Launch Complex 40 at Cape Canaveral following a pair of launch scrubs last week on Nov. 25 and Thanksgiving Day Nov. 28 caused by technical problems with the first stage engine.
The booster thundered off the pad and pierced the completely cloud free evening sky soon after sunset as the blistering roar rumbled deafeningly all across the space coast viewing area.
The rocket exhaust plume was easily visible for several minutes after liftoff of the historic mission.
Next Generation SpaceX Falcon 9 rocket blasts off with SES-8 communications satellite on Dec. 3, 2013 from Pad 40 at Cape Canaveral, FL. Credit: Ken Kremer/kenkremer.com
The 3,138 kg (6,918 lbs) SES-8 satellite was built by Orbital Sciences for SES and is a hybrid Ku- and Ka-band spacecraft that will provide TV and communications coverage for the South Asia and Asia Pacific regions.
This new version of the Falcon 9 rocket has nearly 50% more thrust compared to the original Falcon 9.
The stakes could not have been higher for the future of SpaceX.
The firms future launch manifest of more than 50 flights for NASA and a variety of commercial entities worth billions of dollars were riding on the success of tonight’s liftoff from Cape Canaveral Air Force Station, Florida.
With 54 satellites in orbit SES is one of the largest commercial telecommunications satellite operators in the world.
The next generation Falcon 9 rocket injected the SES-8 telecommunications to its targeted geostationary transfer orbit flying 295 x 80,000 km above Earth.
A restart of the second stage engine was absolutely essential to the success of the mission since a failure to ignite would have doomed the SES-8 satellite from reaching is desired orbit since it’s a requirement for all geostationary transfer missions.
The picture-perfect flight met 100% of the mission objectives, SpaceX said in a post-launch statement.
“The successful insertion of the SES-8 satellite confirms the upgraded Falcon 9 launch vehicle delivers to the industry’s highest performance standards,” said Elon Musk, CEO and Chief Designer of SpaceX.
“As always, SpaceX remains committed to delivering the safest, most reliable launch vehicles on the market today. We appreciate SES’s early confidence in SpaceX and look forward to launching additional SES satellites in the years to come.”
Today’s launch marked SpaceX’s first commercial launch from Florida as well as the first commercial flight from Cape Canaveral Air Force Station in over five years.
Satellite operators have booked their commercial launches with other rocket companies overseas due to the high cost of other American expendable rockets.
SpaceX’s entire corporate aim has been to significantly cut the high cost of access to space.
SpaceX founder and CEO Elon Musk (right) and Martin Halliwell (left), SES chief technical officer briefs reporters including Universe Today on Sunday (Nov. 24) in Cocoa Beach, FL prior to planned SpaceX Falcon 9 rocket blastoff with SES-8 communications satellite from Cape Canaveral, FL. Credit: Ken Kremer/kenkremer.com
With today’s SpaceX is sure to sign even more contracts bringing additional commercial telecommunications satellite space launches back to American soil.
Approximately 185 seconds into flight, the Falcon 9’s second stage equipped with a single Merlin 1-D engine ignited.
It burned for five minutes and 20 seconds to inject SES-8 satellite into its initial parking orbit.
Eighteen minutes later the second stage engine relit for a second time and fired for just over one minute to deliver SES-8 satellite to its final geostationary transfer orbit.
SpaceX Falcon 9 rocket with SES-8 communications satellite soars to orbit. Credit: Ken Kremer/kenkremer.com
This extra powerful new version of the Falcon 9 dubbed v1.1 is powered by a cluster of nine of SpaceX’s new Merlin 1D engines that are about 50% more powerful compared to the standard Merlin 1C engines. The nine Merlin 1D engines 1.3 million pounds of thrust at sea level rises to 1.5 million pounds as the rocket climbs to orbit.
The Merlin 1 D engines are arrayed in an octaweb layout for improved efficiency.
Therefore the upgraded Falcon 9 can boost a much heavier cargo load to the ISS, low Earth orbit, geostationary orbit and beyond.
The next generation Falcon 9 is a monster. It measures 224 feet tall and is 12 feet in diameter. That compares to a 130 foot tall rocket for the original Falcon 9.
Stay tuned here for continuing SpaceX & MAVEN news and Ken’s SpaceX launch reports from on site at Cape Canaveral & the Kennedy Space Center press site.
Learn more about SpaceX, MAVEN, MOM, Mars rovers, Orion and more at Ken’s upcoming presentations
Dec 3/4: “SpaceX launch, MAVEN Mars Launch and Curiosity Explores Mars, Orion and NASA’s Future”, Kennedy Space Center Quality Inn, Titusville, FL, 8 PM
Dec 11: “Curiosity, MAVEN and the Search for Life on Mars”, “LADEE & Antares ISS Launches from Virginia”, Rittenhouse Astronomical Society, Franklin Institute, Phila, PA, 8 PM
SpaceX CEO Elon Musk and Ken Kremer of Universe Today discuss Falcon 9/SES-8 launch by SpaceX Mission Control at Cape Canaveral Air Force Station. Florida. Credit: Ken Kremer/kenkremer.com
To determine what’s in the atmosphere of an exoplanet, astronomers watch the planet pass in front of its host star and look at which wavelengths of light are transmitted and which are partially absorbed. Credit:
NASA's Goddard Space Flight Center
For the first time, astronomers have found conclusive evidence of water in the hazy atmospheres of planets orbiting other stars. Using the Hubble Space Telescope, two teams of scientists found faint but clear signatures of water in the atmospheres of five exoplanets. All five are so-called ‘hot Jupiters,’ massive worlds that orbit close to their host stars.
“To actually detect the atmosphere of an exoplanet is extraordinarily difficult. But we were able to pull out a very clear signal, and it is water,” said Drake Deming from the University of Maryland, who led a study characterizing the atmospheres of two of the five planets.
“We’re very confident that we see a water signature for multiple planets,” said Avi Mandell, a planetary scientist at NASA’s Goddard Space Flight Center, and lead author of another paper on the remaining three exoplanets. “This work really opens the door for comparing how much water is present in atmospheres on different kinds of exoplanets, for example hotter versus cooler ones.”
The five planets are all well-studied, and would not be friendly places for life as we know it — with blazing temperatures and unusual conditions. WASP-17b is an unusual planet in a retrograde orbit, and sodium had already been detected in its atmosphere.
The atmosphere of WASP-12b already has been found to hold vast amounts of carbon as well as water. WASP-19b orbits a nearby star, and has one of the shortest orbital periods of any known planetary body, about 0.7888399 days or approximately 18.932 hours. XO-1b has the distinction of being discovered by amateur astronomers
The astronomers involved in the new studies say the strengths of the water signatures in each world varied, with WASP-17b and HD209458b having the strongest signals.
Currently, studying exoplanet atmospheres can be done when the planets are passing in front of their stars. Researchers can identify the gases in a planet’s atmosphere by determining which wavelengths of the star’s light are transmitted and which are partially absorbed. Deming’s team employed a new technique with longer exposure times, which increased the sensitivity of their measurements.
In both studies, scientists used Hubble’s Wide Field Camera 3 to explore the details of absorption of light through the planets’ atmospheres. The observations were made in a range of infrared wavelengths where a pattern that signifies the presence of water would appear if water were present. The teams compared the shapes and intensities of the absorption profiles, and the consistency of the signatures gave them confidence they saw water.
“These studies, combined with other Hubble observations, are showing us that there are a surprisingly large number of systems for which the signal of water is either attenuated or completely absent,” said Heather Knutson of the California Institute of Technology, a co-author on Deming’s paper. “This suggests that cloudy or hazy atmospheres may in fact be rather common for hot Jupiters.”
