This picture, apparently the first verifiable photo of the Great Wall of China shot from low Earth orbit, was taken by International Space Station Commander Leroy Chiao on Nov. 24, 2004. Credit: NASA
One popular myth about space exploration is that the Great Wall of China is the only human-built structure that can be seen from space. But this is not true. The reality is that you can’t easily see the Great Wall with the unaided eye, even from low Earth orbit. And certainly, the Apollo astronauts couldn’t see it from the Moon, even though that urban legend has been widely circulated.
Canadian astronaut Chris Hadfield, who spent five months aboard the International Space Station in 2012-2013, reiterated the facts about the Great Wall’s visibility from space.
“The Great Wall of China is not visible from orbit with the naked eye,” Hadfield said via Twitter. “It’s too narrow, and it follows the natural contours and colours [of the landscape].”
Additionally, when China’s first astronaut, Yang Liwei, went into space in 2003, he said that he couldn’t see the structure of the Great Wall from out his capsule window.
NASA has confirmed that US astronaut Leroy Chiao took what is thought to be the first verifiable image of the Great Wall of China from out his window on the International Space Station in 2004, using a zoom lens. He photographed a region of Inner Mongolia, about 200 miles north of Beijing, but said Chiao himself said he didn’t see the wall with his unaided eyes, and wasn’t sure if the picture showed it.
The image above was taken with a 180mm zoom lens. If you can’t make out the Great Wall in the image above, here’s a cropped version of the image with annotation to help make out the feature:
This photo of central Inner Mongolia, about 200 miles north of Beijing, was taken on Nov. 24, 2004, from the International Space Station. The yellow arrow points to an estimated location of 42.5N 117.4E where the wall is visible. The red arrows point to other visible sections of the wall. Credit: NASA.
What human-made structures are visible from space? Space Station astronauts have said the ancient pyramids at Giza are relatively easy to see out the window, but most visible are roads or long bridges across straits. Those features stand out as straight lines on the landscape, such as this image shared by Chris Hadfield:
‘One straight human line drawn onto incredibly rough terrain,’ said astronaut Chris Hadfield about this image. Credit: NASA/CSA/Chris Hadfield.
And, of course, at night cities are visible from space because the light they produce. You can see some stunning images here that NASA released in 2012 from the Suomi NPP satellite of city lights from space.
The Apollo astronauts confirmed that you can’t see the Great Wall of China from the Moon. In fact, all you can see from the Moon is the white and blue marble of our home planet.
With all of the human construction, many buildings and other structures can be seen from space. But you can’t see the Great Wall of China from space.
The Blue Marble image of Earth from Apollo 17. Credit: NASA
The track of the tornado that struck Moore, Oklahoma on May 20, 2013 is visible from space in this false color image taken on June 2, 2013 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite.
The tornado that devastated the region around Moore and Newcastle, Oklahoma on May 20, 2013 has been determined to be an EF-5 tornado, the most severe on the enhanced Fujita scale, and has been called one of the most powerful and destructive tornadoes ever recorded. In this new image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite, the scar of destruction on the Oklahoma landscape is clearly visible from space. In this false-color infrared image, red highlights vegetation, and the tornado track appears as a beige strip running west to east across this image; the color reveals the lack of vegetation in the wake of the storm.
According to the National Weather Service, the tornado was on the ground for 39 minutes, ripping across 17 miles (27 kilometers) from 4.4 miles west of Newcastle to 4.8 miles east of Moore. At its peak, the funnel cloud was 1.3 miles (2.1 kilometers) wide and wind speeds reached 210 miles (340 km) per hour. The storm killed at least 24 people, injured 377, and affected nearly 33,000 in some way.
In this image, infrared, red, and green wavelengths of light have been combined to better distinguish between water, vegetation, bare ground, and human developments. Water is blue. Buildings and paved surfaces are blue-gray.
You can also see an interactive satellite map from Google and Digital Globe, showing detail of every building that was damaged or destroyed. Satellite data like this are helping to assist in the recovery and rebuilding of the area. Satellite imagery can provide a systematic approach to aiding, monitoring and evaluating the process.
The highly acclaimed and mind-expanding documentary, ‘Journey of the Universe’, which aired on PBS in 2011, looked at modern science and ancient wisdom to ask the eternal question, why are we on this planet? Hosted by philosopher Brian Thomas Swimme, the film was a journey through time, looking at the evolution of our understandings of science and the world around us, and how we have looked out to try and determine our connection to the cosmos.
Now, the same producers have a new series called ‘Journey of the Universe: Conversations,’ which presents interviews hosted by Mary Evelyn Tucker, an historian of religions, talking with some of the greatest minds of our time — scientists, historians and environmentalists — to explore the unfolding story of Earth, the Universe, and how we should responding to global and environmental issues of the day.
Universe Today has one copy of ‘Journey of the Universe’ and two DVD sets of Journey of the Universe: Conversations’ to give away to our readers. The DVD sets are a 10 hour, 20-part, 4-disc set, just released today. The set is about $80 USD on Amazon.
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday June 10, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
“Conversations” follows in the traditions of discussions by Thomas Berry and Joseph Campbell, and deliberates history and future of the Universe, delving into discussions of science, technology, literature, religion and philosophy.
Wide Field view of IC 443 and IC 444 in Gemini. Credit and copyright: Martin Campbell.
Speaking of shots of awe, here’s an amazingly beautiful wide-field view of IC 443 (also known as the Jellyfish Nebula) a supernova remnant, as well as IC 444, a small reflection nebula, together in the constellation Gemini, surrounded by a sea of stars. Astrophotographer Martin Campbell put this image together by stacking 30 images, totalling 1.5 hours of exposure. His equipment was a Takahashi Epsilon 180 and a modified Canon 5D MKII DSLR.
Gorgeous!
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Ever find yourself thinking about how the Universe came to be, or how humans have evolved to their current level of intelligence, or just why that certain song tugs at your heartstrings? Self-professed wonder junkie Jason Silva has a new video series that feature his reflections on the human condition, the nature of what it means to be alive, and the role of philosophy in everyday life.
Called “Shots of Awe” these under three-minute videos are what Silva calls “inspired nuggets of techno-rapture,” and every week can provide a nudge to contemplate your life; whether it be to look at the complex systems of society, technology, or the beauty of nature and science.
Hang on, though; Silva’s faster-than-thought dialogue takes you for a ride that might leave you spinning … but in a good way!
There are new episodes every Tuesday and below is today’s newest, titled “Singularity.”
A sequence of images showing the light echo (circled) enshrouding T Pyxidis months after the April 2011 outburst. (Credit: NASA/ESA/A. Crotts/J. Sokoloski, H. Uthas & S. Lawrence).
Some of the most violent events in our Universe were the topic of discussion this morning at the 222nd meeting of the American Astronomical Society in Indianapolis, Indiana as researchers revealed recent observations of light echoes seen as the result of stellar explosions.
A light echo occurs when we see dust and ejected material illuminated by a brilliant nova. A similar phenomenon results in what is termed as a reflection nebula. A star is said to go nova when a white dwarf star siphons off material from a companion star. This accumulated hydrogen builds up under terrific pressure, sparking a brief outburst of nuclear fusion.
A very special and rare case is a class of cataclysmic variables known as recurrent novae. Less than dozen of these types of stars are known of in our galaxy, and the most famous and bizarre case is that of T Pyxidis.
Located in the southern constellation of Pyxis, T Pyxidis generally hovers around +15th magnitude, a faint target even in a large backyard telescope. It has been prone, however, to great outbursts approaching naked eye brightness roughly every 20 years to magnitude +6.4. That’s a change in brightness almost 4,000-fold.
But the mystery has only deepened surrounding this star. Eight outbursts were monitored by astronomers from 1890 to 1966, and then… nothing. For decades, T Pyxidis was silent. Speculation shifted from when T Pyxidis would pop to why this star was suddenly undergoing a lengthy phase of silence.
Could models for recurrent novae be in need of an overhaul?
T Pyxidis finally answered astronomers’ questions in 2011, undergoing its first outburst in 45 years. And this time, they had the Hubble Space Telescope on hand to witness the event.
Light curve of the 2011 eruption of T Pyxidis. (Credit: AAVSO).
In fact, Hubble had just been refurbished during the final visit of the space shuttle Atlantis to the orbiting observatory in 2009 on STS-125 with the installation of its Wide Field Camera 3, which was used to monitor the outburst of T Pyxidis.
The Hubble observation of the light echo provided some surprises for astronomers as well.
“We fully expected this to be a spherical shell,” Said Columbia University’s Arlin Crotts, referring to the ejecta in the vicinity of the star. “This observation shows it is a disk, and it is populated with fast-moving ejecta from previous outbursts.”
Indeed, this discovery raises some exciting possibilities, such as providing researchers with the ability to map the anatomy of previous outbursts from the star as the light echo evolves and illuminates the 3-D interior of the disk like a Chinese lantern. The disk is inclined about 30 degrees to our line of sight, and researchers suggest that the companion star may play a role in the molding of its structure from a sphere into a disk. The disk of material surrounding T Pyxidis is huge, about 1 light year across. This results in an apparent ring diameter of 6 arc seconds (about 1/8th the apparent size of Jupiter at opposition) as seen from our Earthly vantage point.
Paradoxically, light echoes can appear to move at superluminal speeds. This illusion is a result of the geometry of the path that the light takes to reach the observer, crossing similar distances but arriving at different times.
And speaking of distance, measurement of the light echoes has given astronomers another surprise. T Pyxidis is located about 15,500 light years distant, at the higher 10% end of the previous 6,500-16,000 light year estimated range. This means that T Pyxidis is an intrinsically bright object, and its outbursts are even more energetic than thought.
Light echoes have been studied surrounding other novae, but this has been the first time that scientists have been able to map them extensively in 3 dimensions.
An artist’s conception of the disk of material surrounding T Pyxidis. (Credit: ESA/NASA & A. Feild STScl/AURA).
“We’ve all seen how light from fireworks shells during the grand finale will light up the smoke and soot from the shells earlier in the show,” said team member Stephen Lawrence of Hofstra University. “In an analogous way, we’re using light from T Pyx’s latest outburst and its propagation at the speed of light to dissect its fireworks displays from decades past.”
Researchers also told Universe Today of the role which amateur astronomers have played in monitoring these outbursts. Only so much “scope time” exists, very little of which can be allocated exclusively to the study of light echoes. Amateurs and members of the American Association of Variable Star Observers (AAVSO) are often the first to alert the pros that an outburst is underway. A famous example of this occurred in 2010, when Florida-based backyard observer Barbara Harris was the first to spot an outburst from recurrent novae U Scorpii.
And although T Pyxidis may now be dormant for the next few decades, there are several other recurrent novae worth continued scrutiny:
Name
Max brightness
Right Ascension
Declination
Last Eruption
Period(years)
U Scorpii
+7.5
16H 22’ 31”
-17° 52’ 43”
2010
10
T Pyxidis
+6.4
9H 04’ 42”
-32° 22’ 48”
2011
20
RS Ophiuchi
+4.8
17H 50’ 13”
-6° 42’ 28”
2006
10-20
T Coronae Borealis
+2.5
15H 59’ 30”
25° 55’ 13”
1946
80?
WZ Sagittae
+7.0
20H 07’ 37”
+17° 42’ 15”
2001
30
Clearly, recurrent novae have a tale to tell us of the role they play in the cosmos. Congrats to Lawrence and team on the discovery… keep an eye out from future fireworks from this rare class of star!
Artist's concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a "hot Jupiter"). Credit: NASA/JPL-Caltech)
Overheated and overinflated, hot Jupiters are some of the strangest extrasolar planets to be discovered by the Kepler mission… and they may be even more exotic than anyone ever thought. A new model proposed by Florida Gulf Coast University astronomer Dr. Derek Buzasi suggests that these worlds are intensely affected by electric currents that link them to their host stars. In Dr. Buzasi’s model, electric currents arising from interactions between the planet’s magnetic field and their star’s stellar wind flow through the interior of the planet, puffing it up and heating it like an electric toaster.
In effect, hot Jupiters are behaving like giant resistors within exoplanetary systems.
Many of the planets found by the Kepler mission are of a type known as “hot Jupiters.” While about the same size as Jupiter in our own solar system, these exoplanets are located much closer to their host stars than Mercury is to the Sun — meaning that their atmospheres are heated to several thousands of degrees.
One problem scientists have had in understanding hot Jupiters is that many are inflated to sizes larger than expected for planets so close to their stars. Explanations for the “puffiness” of these exoplanets have generally involved some kind of extra heating process — but no model successfully explains the observation that more magnetically active stars tend to have puffier hot Jupiters orbiting around them.
“This kind of electric heating doesn’t happen very effectively on planets in our solar system because their outer atmospheres are cold and don’t conduct electricity very well,” says Dr. Buzasi. “But heat up the atmosphere by moving the planet closer to its star and now very large currents can flow, which delivers extra heat to the deep interior of the planet — just where we need it.”
More magnetically active stars have more energetic winds, and would provide larger currents — and thus more heat — to their planets.
The currents start in the magnetosphere, the area where the stellar wind meets the planetary magnetic field, and enter the planet near its north and south poles. This so-called “global electric circuit” (GEC) exists on Earth as well, but the currents involved are only a few thousand amps at 100,000 volts or less.
On the hot Jupiters, though, currents can amount to billions of amps at voltages of millions of volts — a “significant current,” according to Dr. Buzasi.
A Spitzer-generated exoplanet weather map showing temperatures on hot Jupiter HAT-P-2b.
“It is believed that these hot Jupiter planets formed farther out and migrated inwards later, but we don’t yet fully understand the details of the migration mechanism,” Dr. Buzasi says. “The better we can model how these planets are built, the better we can understand how solar systems form. That in turn, would help astronomers understand why our solar system is different from most, and how it got that way.”
Other electrical heating processes have previously been suggested by other researchers as well, once hints of magnetic fields in exoplanets were discovered in 2003 and models of atmospheric wind drag — generating frictional heating — as a result of moving through these fields were made in 2010.
(And before anyone attempts to suggest this process supports the alternative “electric universe” (EU) theory… um, no.)
“No, nothing EU-like at all in my model,” Dr. Buzasi told Universe Today in an email. “I just look at how the field aligned currents that we see in the terrestrial magnetosphere/ionosphere act in a hot Jupiter environment, and it turns out that a significant fraction of the resulting circuit closes inside the planet (in the outer 10% of the radius, mostly) where it deposits a meaningful amount of heat.”
“Being gay doesn’t necessarily define you, it’s just one factor of who you are.”
– NASA Johnson Space Center Deputy Chief of Staff
For over 50 years NASA has inspired people of all ages around the world to set their sights above the sky, to believe in the power of innovation and to not only hope for a better future, but to make it happen. Now, in celebration of LGBT Equality Month, team members from NASA’s Johnson Space Center (and a certain former Starfleet helmsman) tell young people struggling with their identity, “it gets better.”
It’s yet another example of NASA’s commitment to inspiration — regardless of your orientation.
The NASA JSC It Gets Better video is a video project created by the “Out & Allied @ JSC Employee Resource Group” of NASA’s Johnson Space Center. It was created as an outreach tool primarily directed at high school and college-aged lesbian, gay, bisexual, transgender, queer and questioning (LGBTQ) individuals who are victims of bullying and/or have been affected by bullying. This video sends the message to current and future NASA employees that it is OK to be LGBTQ, and that NASA JSC management supports and encourages an inclusive, diverse workforce in our workplace.
Established in 1961 as the Manned Spaceflight Center, NASA’s Johnson Space Center has served as a hub of human spaceflight activity for more than half a century. As the nucleus of the nation’s astronaut corps and home to International Space Station mission operations and a host of future space developments, the center plays a pivotal role in surpassing the physical boundaries of Earth and enhancing technological and scientific knowledge to benefit all of humankind.
An artist's conception of a hypervelocity star that has escaped the Milky Way. Credit: NASA
The Sun is racing through the Galaxy at a speed that is 30 times greater than a space shuttle in orbit (clocking in at 220 km/s with respect to the galactic center). Most stars within the Milky Way travel at a relatively similar speed. But certain stars are definitely breaking the stellar speed limit. About one in a billion stars travel at a speed roughly 3 times greater than our Sun – so fast that they can easily escape the galaxy entirely!
We have discovered dozens of these so-called hypervelocity stars. But how exactly do these stars reach such high speeds? Astronomers from the University of Leicester may have found the answer.
The first clue comes in observing hypervelocity stars, where we can note their speed and direction. From these two measurements, we can trace these stars backward in order to find their origin. Results show that most hypervelocity stars begin moving quickly in the Galactic Center.
We now have a rough idea of where these stars gain their speed, but not how they reach such high velocities. Astronomers think two processes are likely to kick stars to such great speeds. The first process involves an interaction with the supermassive black hole (Sgr A*) at the center of our Galaxy. When a binary star system wanders too close to Sgr A*, one star is likely to be captured, while the other star is likely to be flung away from the black hole at an alarming rate.
The second process involves a supernova explosion in a binary system. Dr. Kastytis Zubovas, lead author on the paper summarized here, told Universe Today, “Supernova explosions in binary systems disrupt those systems and allow the remaining star to fly away, sometimes with enough velocity to escape the Galaxy.”
There is, however, one caveat. Binary stars in the center of our Galaxy will both be orbiting each other and orbiting Sgr A*. They will have two velocities associated with them. “If the velocity of the star around the binary’s center of mass happens to line up closely with the velocity of the center of mass around the supermassive black hole, the combined velocity may be large enough to escape the Galaxy altogether,” explained Zubovas.
In this case, we can’t sit around and wait to observe a supernova explosion breaking up a binary system. We would have to be very lucky to catch that! Instead, astronomers rely on computer modeling to recreate the physics of such an event. They set up multiple calculations in order to determine the statistical probability that the event will occur, and check if the results match observations.
Astronomers from the University of Leicester did just this. Their model includes multiple input parameters, such as the number of binaries, their initial locations, and their orbital parameters. It then calculates when a star might undergo a supernova explosion, and depending on the position of the two stars at that time, the final velocity of the remaining star.
The probability that a supernova disrupts a binary system is greater than 93%. But does the secondary star then escape from the galactic center? Yes, 4 – 25% of the time. Zubovas described, “Even though this is a very rare occurrence, we may expect several tens of such stars to be created over 100 million years.” The final results suggest that this model ejects stars with rates high enough to match the observed number of hypervelocity stars.
Not only do the number of hypervelocity stars match observations but also their distribution throughout space. “Hypervelocity stars produced by our supernova disruption method are not evenly distributed on the sky,” said Dr. Graham Wynn, a co-author on the paper. “They follow a pattern which retains an imprint of the stellar disk they formed in. Observed hypervelocity stars are seen to follow a pattern much like this.”
In the end, the model was very successful at describing the observed properties of hypervelocity stars. Future research will include a more detailed model that will allow astronomers to understand the ultimate fate of hypervelocity stars, the effect that supernova explosions have on their surroundings, and the galactic center itself.
It’s likely that both scenarios – binary systems interacting with the supermassive black hole and one undergoing a supernova explosion – form hypervelocity stars. Studying both will continue to answer questions about how these speedy stars form.
An ultraviolet view of the Large Magellanic Cloud from Swift's Ultraviolet/Optical Telescope. Almost 1 million ultraviolet sources are visible in the image, which took 5.4 days of cumulative exposure to do. The wavelengths of UV shown in this picture are mostly blocked on Earth's surface. Credit: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)
Earth’s galactic next-door neighbors shine brighter than ever in new pictures taken by an orbiting telescope, focusing on ultraviolet light that is tricky to image from the surface.
The Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) — the two largest major galaxies near our own, the Milky Way — were imaged in 5.4 days and 1.8 days of cumulative exposure time, respectively. These produced two gorgeous, high-resolution photos in a spot of the light spectrum normally invisible to humans.
“Prior to these images, there were relatively few UV observations of these galaxies, and none at high resolution across such wide areas, so this project fills in a major missing piece of the scientific puzzle,” stated Michael Siegel, lead scientist for Swift’s Ultraviolet/Optical Telescope at the Swift Mission Operations Center at Pennsylvania State University.
Science isn’t interested in these pictures — taken in wavelengths ranging from 1,600 to 3,300 angstroms, mostly blocked in Earth’s atmosphere — because of their pretty face, however. Ultraviolet light pictures let the hottest stars and star-forming areas shine out, while in visible light those hotspots are suppressed.
“With these mosaics, we can study how stars are born and evolve across each galaxy in a single view, something that’s very difficult to accomplish for our own galaxy because of our location inside it,” stated Stefan Immler, an associate research scientist at NASA Goddard Space Flight Center and the lead of the SWIFT guest investigator program.
The Small Magellanic Cloud as seen by Swift’s Ultraviolet/Optical Telescope. This composite of 656 separate pictures has a cumulative exposure time of 1.8 days. Credit: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)
Although the galaxies are relatively small, they easily shine in our night sky because they’re so close to Earth — 163,000 light-years for the LMC, and 200,000 light years for the SMC.
The LMC is only about 1/10 of the Milky Way’s size, with 1% of the Milky Way’s mass. The punier SMC is half of LMC’s size with only two-thirds of that galaxy’s mass.
Immler revealed the large images — 160 megapixels for the LMC, and 57 megapixels for the SMC — at the American Astronomical Society meeting in Indianapolis on Monday (June 3.)
