Radar images of asteroid 1998 QE2 and its satellite on June 7. Each frame in the animation is a sum of 4 images, spaced apart by about 10 minutes. (Arecibo Observatory/NASA/Ellen Howell)
On the last day of May 2013 asteroid 1998 QE2 passed relatively closely by our planet, coming within 6 million kilometers… about 15 times the distance to the Moon. While there was never any chance of an impact by the 3 km-wide asteroid and its surprise 750 meter satellite, astronomers didn’t miss out on the chance to observe the visiting duo as they soared past as it was a prime opportunity to learn more about two unfamiliar members of the Solar System.
By bouncing radar waves off 1998 QE2 from the giant dish at the Arecibo Observatory in Puerto Rico, researchers were able to construct visible images of the asteroid and its ocean-liner-sized moon, as well as obtain spectrum data from NASA’s infrared telescope in Hawaii. What they discovered was quite surprising: QE2 is nothing like any asteroid ever seen near Earth.
The 305-meter dish at Arecibo Observatory in Puerto Rico (Image courtesy of the NAIC – Arecibo Observatory, a facility of the NSF)
Both Arecibo Observatory and NASA’s Goldstone Deep Space Communications Complex in California are unique among telescopes on Earth for their ability to resolve features on asteroids when optical telescopes on the ground merely see them as simple points of light. Sensitive radio receivers collect radio signals reflected from the asteroids, and computers turn the radio echoes into images that show features such as craters and, in 1998 QE2’s case, a small orbiting moon.
QE2’s moon appears brighter than the asteroid as it is rotating more slowly; thus its Doppler echoes compress along the Doppler axis of the image and appear stronger.
Of the asteroids that come close to Earth approximately one out of six have moons. Dr. Patrick Taylor, a USRA research astronomer at Arecibo, remarked that “QE2’s moon is roughly one-quarter the size of the main asteroid,” which itself is a lumpy, battered world.
Dr. Taylor also noted that our own Moon is a quarter the size of Earth.
QE2’s moon will help scientists determine the mass of the main asteroid and what minerals make up the asteroid-moon system. “Being able to determine its mass from the moon helps us understand better the asteroid’s material,” said Dr. Ellen Howell, a USRA research astronomer at Arecibo Observatory who took both radar images of the asteroid at Arecibo and optical and infrared images using the Infrared Telescope Facility in Hawaii. While the optical images do not show detail of the asteroid’s surface, like the radar images do, instead they allow for measurements of what it is made of.
“What makes this asteroid so interesting, aside from being an excellent target for radar imaging,” Howell said, “is the color and small moon.”
Radar images of asteroid 1998 QE2 and its satellite (top) on June 6. (Arecibo Observatory/NASA/Ellen Howell)
“Asteroid QE2 is dark, red, and primitive – that is, it hasn’t been heated or melted as much as other asteroids,” continued Howell. “QE2 is nothing like any asteroid we’ve visited with a spacecraft, or plan to, or that we have meteorites from. It’s an entirely new beast in the menagerie of asteroids near Earth.”
Spectrum of 1998 QE2 taken May 30 at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea was “red sloped and linear,” indicating a primitive composition not matching any meteorites currently in their collection.
For more radar images of 1998 QE2, visit the Arecibo planetary radar page here.
Source: Universities Space Research Association press release.
Soviet Cosmonaut Valentina Tereshkova was the first woman launched to space 50 years ago aboard Vostok on June 16, 1963. Credit: Roscosmos
50 Years ago today, Soviet Cosmonaut Valentina Tereshkova made history and became the first woman ever fly in space, when she launched aboard the Vostok-6 capsule on June 16, 1963.
Her mission was far longer, lasting nearly 3 days (70 hours 50 minutes) for a total of 48 orbits of Earth at altitudes ranging from 180 to 230 kilometers (110 x 144 mi). She conducted biomedical & science experiments to learn about the effects of space on the human body, took photographs that helped identify aerosols in the atmosphere and manually piloted the ship.
“Hey, sky! Take off your hat, I’m coming!” she said in the seconds prior to liftoff.
Vostok-6 was her only space mission.
First woman in space Soviet cosmonaut Valentina Tereshkova is seen during a training session aboard a Vostok spacecraft simulator on January 17, 1964. Credit: AFP Photo / RIA Novosti
But today at age 76, Tereshkova is ready to forget retirement and sign up for a truly grand space adventure – a trip to Mars.
“I am ready [to go to Mars],” she said in remarks on the occasion of the 50th anniversary of her June 16, 1963 blastoff, according to Roscosmos, the Russian Federal Space Agency. Apparently Mars is her favorite planet!
“Of course, it’s a dream to go to Mars and find out whether there was life there or not,” Tereshkova said. “If there was, then why did it die out? What sort of catastrophe happened?”
Valentina Tereshkova today at age 76 – ready for a Mission to Mars. Credit: RIA Novosti
Tereshkova’s landmark flight on Vostok-6 was made ever more historic in that it was actually a joint space mission with Vostok-5; which blasted off barely two days earlier on June 14 with fellow Soviet cosmonaut Valery Bykovsky.
Vostok-5 and Vostok-6 flew within 5 kilometers (3 miles) of one other at one point. They spoke to each other by radio as well as with the legendary Soviet Premier Nikita Krushchev. Her call sign was “Seagull”. Bykovsky’s call sign was “Hawk”.
Sergei Korolyov, the father of the Soviet space program, called her “my little seagull.”
Korolev wanted to launch a woman to space to score another spectacular first for the Soviet Union at the height of the Cold War with the United States.
So she had been selected as a member of the cosmonaut corps just a year earlier in March 1962 along with four other female candidates. Teseshkova was the only member of that female group ever to achieve orbit.
Sergei Korolev, founder of the Soviet Space program, and Valentina Tereshkova. Credit: Roscosmos
Tereshkova, a textile factory worker, was chosen in part because she was an expert parachute jumper – a key requirement at that time since the Vostok capsule itself could not land safely. So the cosmonauts had to eject in the last moments of the descent from orbit at about 7,000 m (23,000 ft) and descend separately via parachute.
It would take nearly two decades before another woman – also Soviet- would fly to space; Svetlana Savitskaya in 1982.
The first American female space flyer – Sally Ride – finally reached orbit a year later in 1983 aboard the Space Shuttle.
To date, woman comprise about 10% of the people who have flown to space-57 out of 534.
Today, June 16, there are two women orbiting Earth out of 9 humans total – NASA Astronaut Karen Nyberg aboard the International Space Station and Chinese astronaut Wang Yaping aboard Shenzhou 10.
Vostok-6 was the last of the Vostok spacecraft series.
Bykovsky flew a total of 5 days and 82 orbits. He landed 3 hours after Tereshkova on June 19.
Tereshkova became an instant heroine upon landing, a ‘Hero of the Soviet Union’ and will forever be known as the ‘First Lady of Space.’
On June 14, Russian Television aired a special 50th anniversary program celebrating the flights of Vostok-5 and Vostok-6 – “Valentina Tereshkova – Seagull and the Hawk”
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
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Learn more about Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations
June 23: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
In the latest budget proposal for NASA, it appears as though one of NASA’s jewels — education and pubic outreach – is going to take a huge hit. The proposal seeks to slash NASA’s education budget by about a third, going from $137 million to $94 million. Also proposed is an initiative to combine (and in effect, water down) what NASA does by consolidating different educational efforts across the nation.
The American Astronomical Society issued a statement saying that the proposed cuts “would dismantle some of the nation’s most inspiring and successful STEM education assets.”
Dr. Pamela Gay, who heads up a big educational and citizen science effort with Cosmoquest, has writtenpassionately about how these proposed cuts as well as the current sequestration of US governmental agencies will affect not only her work with education and citizen science, but educational programs for schools and universities across the US. Additionally, people who work in these areas face job losses.
So faced with funding cuts, the Cosmoquest team has decided to try an old-fashioned tele-thon (remember Jerry Lewis and his MDA telethons every year?) using new technology.
It starts at Noon EDT, 16:00 UTC on June 15, 2013 and will feature guests like Phil Plait (the Bad Astronomer), NASA scientists and educators, the cast of Beyond the Wall, Mat Kaplan from Planetary Radio, and our very own Fraser Cain. Yours truly might make an appearance as well, beaming in from the middle of nowhere in Minnesota.
As the CosmoQuest team said, they want to make sure astronomy education survives and remains strong. “While one team, and one telethon can’t fix everything, they hope this event can raise awareness, while protected one small corner of astronomy research and education.”
Education and technology are so important for our world’s future; if you can support this effort in any way, it would be greatly appreciated.
A 12-photo panoramic of the milky way arching over Saguaro National Park in Tucson, Arizona. Credit and copyright: Sean Parker/Sean Parker Photography.
The desert provides some of the most stunning landscapes and skycapes, as evidenced by two recent astrophotos from Universe Today readers. The gorgeous lead image by Sean Parker of Tucson, Arizona is a 12-image panoramic view of the Milky Way arching over Saguaro National Park in Tucson, Arizona. Sean noted on Flickr that if you live in Tucson, you can see this photo in a 12×36 frame at Black Crown Coffee Co for the next 3 weeks during his Astrophotography Exhibition. If you go, tell him Universe Today sent you!
The stunning image below is a frame from a timelapse being worked on by Ken Brandon of California. The image was taken on June 9, 2013 and features ancient Bristlecone pines in the foreground, with the arch of the Milky Way visible in the sky:
Ancient Bristlecone pines with an even more ancient Milky Way in the background. Credit and copyright: Ken Brandon.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Yuri Gagarin on the way to his historic Vostok launch on April 12, 1961. Image: NASA
On the morning of April 12, 1961, Soviet cosmonaut Yuri Gagarin lifted off aboard Vostok 1 to become the first human in space, spending 108 minutes in orbit before landing via parachute in the Saratov region of the USSR. The soft-spoken and well-mannered Gagarin, just 27 years old at the time, became an instant hero, representing the success of the Soviet space program (Alan Shepard’s shorter, suborbital flight happened less than a month later) to the entire world. Gagarin later went on to become a director for the Cosmonaut Training Center and was preparing for a second space flight. Tragically, he was killed when a MiG-15 aircraft he was piloting crashed on March 27, 1968.
Gagarin’s death has long been shrouded by confusion and controversy, with many theories proposed as to the actual cause. Now, 45 years later, details about what really happened to cause the death of the first man in space have come out — from the first man to go out on a spacewalk, no less.
Televised image of Aleksey Leonov during his spacewalk outside Vokshod 2
According to an article published online today on Russia Today (RT.com) former cosmonaut Aleksey Leonov — who performed the first EVA on March 18, 1965 — has revealed details about the accident that killed both Yuri Gagarin and his flight instructor Vladimir Seryogin in March 1968.
Officially the cause of the crash was said to be the ill-fated result of an attempt to avoid a foreign object during flight training in their MiG-15UTI, a two-seated, dual-controlled training version of the widely-produced Soviet aircraft. “Foreign objects” could be anything, from balloons to flocks of birds to airborne debris to… well, you see where one could go with that. (And over the years many have.)
The maneuver led to the aircraft going into a tailspin and crashing, killing both men. But experienced pilots like Gagarin and Seryogin shouldn’t have lost control of their plane like that — not according to Leonov, who has been trying to release details of the event for the past 20 years… if only that the pilots’ families might know the truth.
A Sukhoi Su-15 fighter jet (Wikipedia Commons)
Now, a declassified report, which Leonov has been permitted to share, shows what actually happened during the training flight: an “unauthorized Su-15 fighter” flew too close to Gagarin’s MiG, disrupting its flight and sending it into a spin.
“In this case, the pilot didn’t follow the book, descending to an altitude of 450 meters,” Leonov says in the RT.com article. “While afterburning the aircraft reduced its echelon at a distance of 10-15 meters in the clouds, passing close to Gagarin, turning his plane and thus sending it into a tailspin — a deep spiral, to be precise — at a speed of 750 kilometers per hour.”
The pilot of the Su-15 — who is still alive — was was not named, a condition of Leonov’s permission to share the information.
According to first woman in space Valentina Tereshkova, who was officially grounded by the government after Gagarin’s death to avoid a loss of another prominent cosmonaut, the details come as a bittersweet relief.
“The only regret here is that it took so long for the truth to be revealed,” Tereshkova said. “But we can finally rest easy.”
Tereshkova and Leonov at the Cosmonautics Museum in Moscow during a ceremony in 2011 celebrating the 50th anniversary of the launch of Yuri Gagarin. (NASA photo.)
The view when ATV-3 approached the ISS in 2012. Credit: NASA.
Recall how during a space shuttle mission, the astronauts were awoken each day with music radioed up from Mission Control? Now, ESA has started a tradition of creating a music video to celebrate various events, such as the docking of their Automated Transfer Vehicle. The ATV-4, named Albert Einstein, will dock with the International Space Station on Saturday, June 15 at 13:46 UTC (9:46 a.m. EDT, and here’s a little hip hop to get you in the mood.
ESA teamed up with hip hop group Ugly Duckling for a super space remix of the song “Elevation.”
The connection to the group and this ATV mission was perfect, as the long-time DJ for Ugly Duckling goes under the stage name DJ Young Einstein. ESA liked the group because they are known for their ‘old-school’ hip-hop with an upbeat message and non-violent lyrics.
TATV-4 is ferrying a record cargo of 6.6 tons to the ISS – food, fuel, water, oxygen, science experiments and undisclosed special treats for the six-member crew on the space station.
An artist's conception of a spacecraft designed to pick up an asteroid. Credit: NASA/Advanced Concepts Laboratory
In a few generations of robotics, we’ll see mighty machines able to fully construct themselves and operate from the surface of asteroids — providing applications for mining, NASA researchers say in a new study.
The scientists are convinced that this type of research is not only possible, but also able to support itself financially. (Costs overruns are a notorious factor in space exploration as it pushes frontiers both literally and engineering-wise.)
“Advances in robotics and additive manufacturing have become game-changing for the prospects of space industry. It has become feasible to bootstrap a self-sustaining, self-expanding industry at reasonably low cost,” the researchers stated in a new study.
A couple of factors are pointing to this, researchers said: private industry is willing and able to get involved. Advances in technologies such as 3-D printing are making off-world work more feasible. Also, humanity’s surveys of space resources has revealed the elements needed to make rubber, plastic and alloys needed for machinery.
NASA proposes a robotic flotilla could mine nearby space rocks. They caution the technology won’t be ready tomorrow, and more surveys will need to be done of nearby asteroids to figure out where to go next. There is, however, enough progress to see building blocks, the agency stated.
An artist’s conception of a space exploration vehicle approaching an asteroid. Credit: NASA
“Robots and machines would just make the metal and propellants for starters,” stated Phil Metzger, a senior research physicist at NASA’s Kennedy Space Center, who led the study.
“The first generation of robots makes the second generation of hardware, except the comparatively lightweight electronics and motors that have to be sent up from Earth. It doesn’t matter how much the large structures weigh because you didn’t have to launch it.”
A computer model in the study showed that in six generations of robotics, these machines will be able to construct themselves and operate without any need of materials from Earth.
Artist impression of the Arkyd Interceptor, a low cost asteroid mission that enables accelerated exploration. Credit: Planetary Resources.
In the past year, members of both firms have proposed asteroid mining ideas, and since then, Planetary Resources has also unveiled other projects such as a public space telescope (perhaps in a bid to diversify revenues and attract more attention.)
That’s received many questions from critics (including at least one government space committee), but NASA has argued it is feasible and a way to unite innovation across various sectors.
“Because asteroids are loaded with minerals that are rare on Earth, near-Earth asteroids and the asteroid belt could become the mining centers for remotely-operated excavators and processing machinery,” NASA stated.
Asteroid 951 Gaspra. Credit: NASA
“In the future, an industry could develop to send refined materials, rare metals and even free, clean energy to Earth from asteroids and other bodies.”
Curiosity’s hi tech ‘hand’ and percussion drill hovers above 2nd bore hole at Cumberland mudstone rock after penetrating laser blasting to unlock secrets of ancient flow of Martian water. Photo mosaic assembled from high resolution Mastcam images on May 21, 2013, Sol 281. Credit: NASA/JPL-Caltech/MSSS/Ken Kremer (kenkremer.com)/Marco Di Lorenzo
Ten months after her breathtaking touchdown on the Red Planet, NASA’s Curiosity rover is nearly set to embark on an epic drive like no other in space history to the slopes of mysterious Mount Sharp – looming supreme inside Gale Crater and the primary mission objective.
But not before the robot completes a few last critical science tasks to more fully illuminate the potential for the origin of Martian microbes in the habitable zone discovered at the work-site of her first penetrations into Mars water altered surface.
The rover science team has chosen a trio of final targets to investigate around the shallow basin of Yellowknife Bay, that resembles a dried out lakebed, where Curiosity has toiled for the past six months, drilled twice into the mudstone outcrops at ‘John Klein’ and ‘Cumberland’ and repeatedly fired her powerful science laser.
Curiosity will revisit a pair of intriguing outcrops named ‘Point Lake’ and ‘Shaler’ that the rover briefly investigated before arriving at ‘John Klein’, said Joy Crisp of JPL, Curiosity’s deputy project scientist, at a media briefing.
“Shaler might be a river deposit. Point Lake might be volcanic or sedimentary. A closer look at them could give us better understanding of how the rocks we sampled with the drill fit into the history of how the environment changed.”
Curiosity will employ nearly all her science instruments to study the outcrops – except the drill.
“It’s highly unlikely to drill at ‘Point Lake’ and ‘Shaler’ because we want to get driving,” Crisp told Universe Today.
“We might drill somewhere along the way to Mount Sharp depending on whether we find something compelling.”
‘Point Lake’ Outcrop in Gale Crater. A priority target for a closer look byCuriosity before the rover departs the “Glenelg” area east of its landing site. The pitted outcrop called “Point Lake” is about 7 feet (2 meters) wide and 20 inches (50 centimeters) high. A closer inspection may yield information about whether it is a volcanic or sedimentary deposit. Credit: NASA/JPL-Caltech/MSSS
Researchers will also use the DAN (Dynamic Albedo of Neutrons) instrument to look for traces of mineral bound water – in the form of hydrogen – at the boundary between bedrock areas of mudstone and sandstone.
Thereafter, Curiosity’s handlers will command the 1 ton behemoth to begin the drive to the lower reaches of Mount Sharp which lies about 6 miles (10 kilometers) distant – as the Martian crow flies.
Mount Sharp rises about 3.4 miles (5.5 km) from the center of Gale Crater. It’s taller than Mount Ranier in Washington State.
Billions of years of Mars geologic history are preserved in the sedimentary layers of Mount Sharp – along with potential signatures of the chemical ingredients of life.
Curiosity Route Map From ‘Glenelg’ to Mount Sharp.
This map shows where NASA’s Mars rover Curiosity landed in August 2012 at “Bradbury Landing”; the area where the rover worked from November 2012 through May 2013 at and near the “John Klein” target rock in the “Glenelg” area; and the mission’s next major destination, the entry point to the base of Mount Sharp. Credit: NASA/JPL-Caltech/Univ. of Arizona
“The drive will start in a few weeks,” said Curiosity Project Manager Jim Erickson of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. at the briefing.
But the team will be on the lookout for targets of opportunity along the way.
“We are on a mission of exploration. If we come across scientifically interesting areas, we are going to stop and examine them before continuing the journey,” Erikson added.
“If we pass something amazing and compelling we might turn around and drive back,” Crisp added.
It could take nearly a year to arrive at Mount Sharp. And Curiosity must pass through a potentially treacherous dune field to get there – see NASA JPL route map above.
“We are looking for the best path though,” said Erickson.
NASA chose Gale as the landing site specifically to dispatch Curiosity to investigate the sedimentary layers of Mount Sharp because it exhibited signatures of clay minerals that form in neutral water and that could possibly support the origin and evolution of simple Martian life forms, past or present.
“We have a real desire to get to Mount Sharp because there we see variations in the mineralogy as we go up from the base to higher levels and a change in the record of the environment,” said Crisp.
Analysis of the initial gray colored, powdery ‘John Klein’ sample by Curiosity’s pair of onboard chemistry labs – SAM & Chemin – revealed that this location on Mars was habitable in the past and possesses the key chemical ingredients – such as clay minerals – required to support microbial life forms- thereby successfully accomplishing the key science objective of the mission and making a historic discovery long before even arriving at destination Mount Sharp.
Besides the science measurements, researchers also learned lot about how to operate the complex drilling and sample delivery mechanisms much more efficiently for the second drilled rock sample.
The sieved and pulverized Cumberland sample was delivered in about a quarter of the time compared to the John Klein sample – accomplished at a deliberately measured and cautious pace.
Context view of Curiosity’s 2nd drill site at Cumberland rock on the floor of Yellowknife Bay basin showing ancient water altered rocks where the rover found environmental conditions favorable for microbial life. Mastcam images on May 23, 2013, Sol 283. Credit: NASA/JPL-Caltech/MSSS/Ken Kremer (kenkremer.com)/Marco Di Lorenzo
Analysis of the “Cumberland” powder is currently in progress. The goal is to determine how it compares chemically and to confirm the results found at ‘John Klein.’
“No results from Cumberland are available yet,” said Crisp.
The robot used the powerful million watt ChemCam laser to blast into the Cumberland drill hole and gray tailings scattered on the surface to glean as much insight and measurements of the chemical composition and transformation by water as possible before departing.
Curiosity has just arrived at “Point Lake’. Stay tuned for my next Curiosity story.
Meanwhile, Curiosity’s older sister rover Opportunity has likewise discovered clay minerals and a habitable zone on the opposite side of the Red Planet – details here.
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
Learn more about Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations
June 23: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
This time lapse mosaic shows Curiosity moving her robotic arm to drill into her 2nd rockt target named “Cumberland” to collect powdery material on May 19, 2013 (Sol 279) for analysis by her onboard chemistry labs; SAM & Chemin. The photomosaic was stitched from raw images captured by the navcam cameras on May 14 & May 19 (Sols 274 & 279). Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo
This is a classic trick question. Ask a friend, “what is the closest star?” and then watch as they try to recall some nearby stars. Sirius maybe? Alpha something or other? Betelgeuse?
The answer, obviously, is the Sun; that massive ball of plasma located a mere 150 million km from Earth.
Let’s be more precise; what’s the closest star to the Sun?
Closest Star
You might have heard that it’s Alpha Centauri, the third brightest star in the sky, just 4.37 light-years from Earth.
But Alpha Centauri isn’t one star, it’s a system of three stars. First, there’s a binary pair, orbiting a common center of gravity every 80 years. Alpha Centauri A is just a little more massive and brighter than the Sun, and Alpha Centauri B is slightly less massive than the Sun. Then there’s a third member of this system, the faint red dwarf star, Proxima Centauri.
It’s the closest star to our Sun, located just a short 4.24 light-years away.
Proxima Centauri
Alpha Centauri is located in the Centaurus constellation, which is only visible in the Southern Hemisphere. Unfortunately, even if you can see the system, you can’t see Proxima Centauri. It’s so dim, you need a need a reasonably powerful telescope to resolve it.
Let’s get sense of scale for just how far away Proxima Centauri really is. Think about the distance from the Earth to Pluto. NASA’s New Horizons spacecraft travels at nearly 60,000 km/h, the fastest a spacecraft has ever traveled in the Solar System. It will have taken more than nine years to make this journey when it arrives in 2015. Travelling at this speed, to get to Proxima Centauri, it would take New Horizons 78,000 years.
Proxima Centauri has been the nearest star for about 32,000 years, and it will hold this record for another 33,000 years. It will make its closest approach to the Sun in about 26,700 years, getting to within 3.11 light-years of Earth. After 33,000 years from now, the nearest star will be Ross 248.
What About the Northern Hemisphere?
Bernard’s StarFor those of us in the Northern Hemisphere, the closest visible star is Barnard’s Star, another red dwarf in the constellation Ophiuchus. Unfortunately, just like Proxima Centauri, it’s too dim to see with the unaided eye.
The closest star that you can see with the naked eye in the Northern Hemisphere is Sirius, the Dog Star. Sirius, has twice the mass and is almost twice the size of the Sun, and it’s the brightest star in the sky. Located 8.6 light-years away in the constellation Canis Major – it’s very familiar as the bright star chasing Orion across the night sky in Winter.
How do Astronomers Measure the Distance to Stars?
They use a technique called parallax. Do a little experiment here. Hold one of your arms out at length and put your thumb up so that it’s beside some distant reference object. Now take turns opening and closing each eye. Notice how your thumb seems to jump back and forth as you switch eyes? That’s the parallax method.
To measure the distance to stars, you measure the angle to a star when the Earth is one side of its orbit; say in the summer. Then you wait 6 month, until the Earth has moved to the opposite side of its orbit, and then measure the angle to the star compared to some distant reference object. If the star is close, the angle will be measurable, and the distance can be calculated.
You can only really measure the distance to the nearest stars this way, since it only works to about 100 light-years.
The 20 Closest Stars
Here is a list of the 20 closest star systems and their distance in light-years. Some of these have multiple stars, but they’re part of the same system.
Alpha Centauri – 4.2
Barnard’s Star – 5.9
Wolf 359 – 7.8
Lalande 21185 – 8.3
Sirius – 8.6
Luyten 726-8 – 8.7
Ross 154 – 9.7
Ross 248 – 10.3
Epsilon Eridani – 10.5
Lacaille 9352 – 10.7
Ross 128 – 10.9
EZ Aquarii – 11.3
Procyon – 11.4
61 Cygni – 11.4
Struve 2398 – 11.5
Groombridge 34 – 11.6
Epison Indi – 11.8
Dx Carncri – 11.8
Tau Ceti – 11.9
GJ 106 – 11.9
According to NASA data, there are 45 stars within 17 light years of the Sun. There are thought to be as many as 200 billion stars in our galaxy. Some are so faint that they are nearly impossible to detect. Maybe, with technological improvements, scientists will find even closer stars.
Dark lightning occurs within thunderstorms and flings gamma rays and antimatter into space. (Science@NASA video)
Discovered “by accident” by NASA’s Fermi Gamma-ray Space Telescope in 2010, dark lightning is a surprisingly powerful — yet invisible — by-product of thunderstorms in Earth’s atmosphere. Like regular lightning, dark lightning is the result of a natural process of charged particles within storm clouds trying to cancel out opposing charges. Unlike normal lightning, though, dark lightning is invisible to our eyes and doesn’t radiate heat or light — instead, it releases bursts of gamma radiation.
What’s more, these gamma-ray outbursts originate at relatively low altitudes well within the storm clouds themselves. This means that airplane pilots and passengers flying through thunderstorms may be getting exposed to gamma rays from dark lightning, which are energetic enough to pass through the hull of an aircraft… as well as anything or anyone inside it. To find out how such exposure to dark lightning could affect air travelers, the U.S. Naval Research Laboratory (NRL) is conducting computer modeling tests using their SoftWare for the Optimization of Radiation Detectors — SWORD, for short.
Terrestrial Gamma-ray Flashes (TGFs) are extremely intense, sub-millisecond bursts of gamma rays and particle beams of matter and anti-matter. First identified in 1994, they are associated with strong thunderstorms and lightning, although scientists do not fully understand the details of the relationship to lightning. The latest theoretical models of TGFs suggest that the particle accelerator that creates the gamma rays is located deep within the atmosphere, at altitudes between six and ten miles, inside thunderclouds and within reach of civilian and military aircraft.
These models also suggest that the particle beams are intense enough to distort and collapse the electric field within thunderstorms and may, therefore, play an important role in regulating the production of visible lightning. Unlike visible lightning, TGF beams are sufficiently broad — perhaps about half a mile wide at the top of the thunderstorm — that they do not create a hot plasma channel and optical flash; hence the name, “dark lightning.”
A team of NRL Space Science Division researchers, led by Dr. J. Eric Grove of the High Energy Space Environment (HESE) Branch, is studying the radiation environment in the vicinity of thunderstorms and dark lightning flashes. Using the Calorimeter built by NRL on NASA’s Fermi Gamma-ray Space Telescope they are measuring the energy content of dark lightning and, for the first time, using gamma rays to geolocate the flashes.
As a next step, Dr. Chul Gwon of the HESE Branch is using NRL’s SoftWare for the Optimization of Radiation Detectors (SWORD) to create the first-ever simulations of a dark lightning flash striking a Boeing 737. He can calculate the radiation dosage to the passengers and crew from these Monte Carlo simulations. Previous estimates have indicated it could be as high as the equivalent of hundreds of chest X-rays, depending on the intensity of the flash and the distance to the source.
Simulation of a Boeing 737 struck by dark lightning. Green tracks show the paths of gamma rays from the dark flash as they enter the aircraft from below. (Credit: U.S. Naval Research Laboratory)
SWORD simulations allow researchers to study in detail the effects of variation in intensity, spectrum, and geometry of the flash. Dr. Grover’s team is now assembling detectors that will be flown on balloons and specialized aircraft into thunderstorms to measure the gamma ray flux in situ. The first balloon flights are scheduled to take place this summer.
