The eight planets of our Solar System vary widely, not only in terms of size, but also in terms of mass and density (i.e. its mass per unit of volume). For instance, the 4 inner planets – those that are closest to the Sun – are all terrestrial planets, meaning they are composed primarily of silicate rocks or metals and have a solid surface. On these planets, density varies the farther one ventures from the surface towards the core, but not considerably.
By contrast, the 4 outer planets are designated as gas giants (and/or ice giants) which are composed primarily of of hydrogen, helium, and water existing in various physical states. While these planets are greater in size and mass, their overall density is much lower. In addition, their density varies considerably between the outer and inner layers, ranging from a liquid state to materials so dense that they become rock-solid.
China's new radio telescope, the world's largest, should be completed by September 2016. Image: FAST
China is building the world’s largest radio telescope, and will have to move almost 10,000 people from the vicinity to guarantee the telescope’s effectiveness. The telescope, called the Five-hundred-meter Aperture Spherical Telescope (FAST), will be completed in September, 2016. At 500 meters in diameter, it will surpass the workhorse Arecibo radio observatory in Puerto Rico, which is 305 meters in diameter.
China has routinely moved large amounts of people to make room for developments like the Three Gorges Dam. But in this case, the people are being moved so that FAST can have a five kilometre radio-quiet buffer around it.
According to China’s news agency Xinhua, an unnamed official said the people are being moved so that the facility can have a “sound electromagnetic wave environment.” Common devices and equipment like microwave ovens, garage door openers, and of course, mobile phones, all create radio waves that FAST will sense and which can interfere with the telescope’s operation.
The telescope’s high level of sensitivity “will help us to search for intelligent life outside of the galaxy,” according to Wu Xiangping, director-general of the Chinese Astronomical Society. But aside from searching for radio waves that could be from distant alien civilizations, like SETI does, the enormous dish will also to be used to study astronomical objects that emit radio signals, like galaxies, pulsars, quasars, and supernovae. The radio signals from these objects can tell us about their mass, and their distance from us. But the signals are very weak, so radio telescopes have to be huge to be effective.
Radio telescopes are also used to send out radio signals and bounce them off objects like asteroids and the other planets in our Solar System. These signals are detected by the telescope when they return to Earth, and used to create images.
Huge radio telescopes like FAST can only be built in certain places. They require a large, naturally dish-shaped area for construction. (Arecibo is built in a huge karst sinkhole in Puerto Rico.) Though FAST is in a fairly remote location, where there are no major cities or towns, there are still approximately 10,000 people who will have to be moved. Most of the people moved will be compensated to the tune of $2500, with some receiving more than that.
The FAST facility is part of a concerted effort by China to be a dominant player in space study and exploration. The Chang e 3 mission to the Moon, with its unmanned lander and rover, showed China’s growing capabilities in space. China also plans to have its own space station, its own space weather station at LaGrange 1, and a mission to Mars by 2020, consisting of an orbiter and a rover.
Construction on FAST began in 2011, and will cost 1.2 billion yuan ($260 million) to build.
This overhead shot of the James Webb Space Telescope shows part of the installation of the 18 primary flight mirrors onto the telescope structure in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credits: NASA’s Goddard Space Flight Center/Chris Gunn
See time-lapse video below
This overhead shot of the James Webb Space Telescope shows part of the installation of the 18 primary flight mirrors onto the telescope structure in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credits: NASA’s Goddard Space Flight Center/Chris Gunn See time-lapse video below
NASA GODDARD SPACE FLIGHT CENTER, MD – A time-lapse video newly released by NASA documents the painstakingly complex assembly of the primary mirror at the heart of the biggest space telescope ever conceived by humankind – NASA’s James Webb Space Telescope (JWST).
Asteroids represent a real danger to Earth. But is targeting them with missiles, maybe nuclear, a good idea? Image: NASA/JPL/CalTech
In a shocking announcement, Russian scientists say they want to test improved ballistic missiles on the asteroid Apophis, which is expected to come dangerously close to Earth in 2036. If this doesn’t send chills down your spine, you haven’t read enough science fiction.
In a February 11th article in the Russian state-owned news agency TASS, Sabit Saitgarayev, the lead researcher at the Makeyev Rocket Design Bureau, says Russian scientists are developing a program to upgrade Inter-Continental Ballistic Missiles (ICBMs) to destroy near-Earth meteors from 20-50 metres in size. Apophis’ approach in 2036 would be a test for this program.
ICBM’s are the kind of long range nukes that the USSR and the USA had pointed at each other for decades during the Cold War. They still have some pointed at each other, and they can be launched quickly. This program would take that technology and improve it for anti-asteroid use.
Typical rockets of the type that take payloads into space are not good candidates for intercepting asteroids. They require too much lead time to meet the threat of an incoming asteroid that might be detected only days before impact. They can take several days to fuel. But ICBM’s are different. They can stand at the ready for long periods of time, and be launched at a moment’s notice. But to be suitable for use as asteroid killers, they have to be upgraded.
Design work on the asteroid-killing ICBM’s has already begun, admitted Saitgarayev, but he did not say whether the money has been committed or whether the authorization has been given to go ahead with the project. But like a lot of things that are said and done by Russia, it’s difficult to know exactly where the truth lies.
There’s no question that being prepared to prevent an asteroid strike on Earth is of the utmost importance. No matter where on Earth one was to strike, the effects could be global. But one thing’s certain: the development and testing of missiles designed to be used in space is unsettling.
It’s also unsettling in light of the January 16th TASS article stating that “The international scientific community has asked Russian scientists to develop an asteroid deflection system on the basis of nuclear explosions in space.” Taken together, the two announcements point towards a program of weaponizing space, something the international community has agreed should be avoided. In fact, there is a ban on nuclear explosions in space.
We don’t want to be alarmist. There are only a handful of countries in the world that have the capacity to develop some protective system against asteroids, and Russia is definitely one of them. And if Earth were threatened by an asteroid, the weaponization of space would be the least of our concerns.
The fact that Russia wants to develop a missile system with nuclear warheads, and employ it in space, is not entirely unreasonable. But it should make us stop and think. What will happen if something goes wrong?
It’s easy to imagine a scenario where an atomic explosion went off in low-Earth orbit. What would the consequences be? And what are the consequences to having one country develop this capability, rather than an international group? How can this whole endeavour be managed responsibly?
A black hole is the final form a massive star collapses to. The light (and spacetime itself) is warped around the black hole's event horizon due to extreme gravitational effects. This is as accurate as we can be to visualizing an actual black hole as it was generated with a code that implemented General Relativity accurately. Credit and Copyright: Paramount Pictures/Warner Bros.
Mathematical Model used to create the image developed by Dr. Kip Thorne
It’s no secret that black holes are objects to be avoided, were you to plot yourself a trip across the galaxy. Get too close to one and you’d find your ship hopelessly caught sliding down a gravitational slippery slope toward an inky black event horizon, beyond which there’s no escape. The closer you got the more gravity would yank at your vessel, increasingly more on the end closest to the black hole than on the farther side until eventually the extreme tidal forces would shear both you and your ship apart. Whatever remained would continue to fall, accelerating and stretching into “spaghettified” strands of ship and crew toward—and across—the event horizon. It’d be the end of the cosmic road, with nothing left of you except perhaps some slowly-dissipating “information” leaking back out into the Universe over the course of millennia in the form of Hawking radiation. Nice knowin’ ya.
That is, of course, if you were foolish enough to approach a non-spinning black hole.* Were it to have a healthy rotation to it there’s a possibility, based on new research, that you and your ship could survive the trip intact.
A team of researchers from Georgia Gwinnett College, UMass Dartmouth, and the University of Maryland have designed new supercomputer models to study the exotic physics of quickly-rotating black holes, a.k.a. Kerr black holes, and what might be found in the mysterious realm beyond the event horizon. What they found was the dynamics of their rapid rotation create a scenario in which a hypothetical spacecraft and crew might avoid gravitational disintegration during approach.
“We developed a first-of-its-kind computer simulation of how physical fields evolve on the approach to the center of a rotating black hole,” said Dr. Lior Burko, associate professor of physics at Georgia Gwinnett College and lead researcher on the study. “It has often been assumed that objects approaching a black hole are crushed by the increasing gravity. However, we found that while gravitational forces increase and become infinite, they do so fast enough that their interaction allows physical objects to stay intact as they move toward the center of the black hole.”
Because the environment around black holes is so intense (and physics inside them doesn’t play by the rules) creating accurate models requires the latest high-tech computing power.
“This has never been done before, although there has been lots of speculation for decades on what actually happens inside a black hole,” said Gaurav Khanna, Associate Physics Professor at UMass Dartmouth, whose Center for Scientific Computing & Visualization Research developed the precision computer modeling necessary for the project.
Artist’s representation of a black hole. Credit: XMM-Newton, ESA, NASA
Like science fiction movies have imagined for decades—from Disney’s The Black Hole to Nolan’s Interstellar—it just might be possible to survive a trip into a black hole, if conditions are right (i.e., you probably still don’t want to find yourself anywhere near one of these.)
Of course, what happens once you’re inside is still anyone’s guess…
The team’s paper “Cauchy-horizon singularity inside perturbed Kerr black holes” was published in the Feb. 9, 2016 edition of Rapid Communication in Physical Review D. You can find the full text here. The research was supported by the National Science Foundation.
*A true non-rotating “Schwarzschild” black hole would not, due to angular momentum etc., be readily found in the real world, thus making this research on rotating black holes all the more essential.
5 Planets Alignment The Moon 01-30-2016, 06:13am EST
outside of Warrenton, Virginia. Image credit and copyright: John Chumack
Canon 6D DSLR, 8mm fisheye Lens, Slightly Cropped ISO 800, 8 second exposure,
Have you seen them? There’s been a quintet of good reasons to awaken early this past week, as the February dawn sky hosts all five classical planets, very nearly in order: Mercury, Venus, Mars, Saturn and Jupiter. For a few days, the waning crescent Moon even joined the show on the weeks leading up to New on February 8th. Fleeting Mercury breaks the streak later this week, exiting the dawn sky as it heads towards superior conjunction on the far side of the Sun on March 23rd. Continue reading “Stunning Images of the February Dawn Planetary Line-up from Around the World”
Messier Object 3, as imaged by Adam Block at Mount Lemmon SkyCenter, University of Arizona. Credit: caelumobservatory.com
During the late 18th century, Charles Messier began to notice a series of “nebulous” objects in the night sky which he originally mistook for comets. With the hope of preventing other astronomers from making the same mistake, he began compiling a list of these in what would come to be known as the Messier Catalog. Consisting of 100 objects, the catalog became an important milestone in the discovery and research of Deep Sky objects.
One such object is Messier Object 3 (aka. M3 or NGC 5272) globular cluster that is located in the northern constellation of Canes Venatici. Since it was first observed, this globular star cluster has gone on to become one of the best-studied objects in the night sky, and is considered by many amateur astronomers to be one of the finest visible clusters.
Mars has a lot of heart (s)! Send one to your Valentine Credit: NASA
Happy Valentine’s Day from the Pluto New Horizon’s mission! Click to download a high resolution pdf file you can print out. Credit: NASA
Still looking for the right card for your sweetheart this Valentine’s Day? Why not do it in cosmic proportion by getting NASA on your side? The tender-hearted folks at agency may have just what you’re looking for.
The staff at the New Horizons mission headquarters offers two valentines this season that play off Pluto’s heart-shaped, icy plain Tombaugh Regio. While the temperature there hovers around 400 below, you’re guaranteed a 98.6° smile when your sweetie opens the card and sees your love reflected in glittering nitrogen ice.
Mars has a lot of heart (s)! Click to select and send your Valentine a Red Planet-themed e-card. Credit: NASA
Pluto not your thing? Select from 12 different Mars e-card love greetings at this NASA site and blow your partner away in a Martian dust devil of love. Many of the heart-shaped features depicted on the cards are genuine features and include collapse pits, craters and mesas.
Click to pick from 8 different valentines at the OSIRIS-Rex asteroid mission site. Credit: NASA
Even the asteroids send their saucy wishes. Check out the delightful series of valentines from the upcoming OSIRIS-Rex sample return mission to 101955 Bennu, slated to launch in September this year and return a sample of the carbonaceousasteroid to Earth in 2023. If you go this route, I’d complement the card with a meal heavy on edible carbonaceous material at your partner’s favorite restaurant.
Happy Valentine’s Day! Spread the love for a happier planet.
A photo of the constellation Andromeda with all Bayer-designated stars marked and the IAU figure drawn in. Credit: Roberto Mura/Wikipedia Commons
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come. Thanks to the development of modern telescopes and astronomy, this list was amended by the early 20th century to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
Of these, Andromeda is one of the oldest and most widely recognized. Located north of the celestial equator, this constellation is part of the family of Perseus, Cassiopeia, and Cepheus. Like many constellation that have come down to us from classical antiquity, the Andromeda constellation has deep roots, which may go all the way back to ancient Babylonian astronomy.
