Artist's concept of OSIRIS-REx at Bennu. (Credit: NASA/GSFC)
I love anything that attempts to provide a sense of scale about the Solar System (see here and here for even more examples) and this one brings us down past the Sun, planets, and moons all the way to asteroid size — specifically asteroid 101955 Bennu, the target of the upcoming OSIRIS-REx mission.
Created by the OSIRIS-REx “321Science!” team, consisting of communicators, film and graphic arts students, teens, scientists, and engineers, the video shows some relative scales of our planet compared to the Sun, and also the actual size of asteroid Bennu in relation to some familiar human-made structures that we’re familiar with. (My personal take-away from this: Bennu — one of those “half grains of sand” — is a rather small target!)
A NASA New Frontiers mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) will launch in Sept. 2016 on a two-year journey to the asteroid 101955 Bennu. Upon arrival OSIRIS-REx will map Bennu’s surface and also measure the Yarkovsky effect, by which asteroids’ trajectories can change over time due to the small force exerted by radiant heat.
Comet 67P/Churyumov-Gerasimenko imaged by OSIRIS on July 29, 2014
WOW! We’re really getting to the good stuff now! This is no computer-generated shape model, this is the real deal: the double-lobed nucleus of Comet 67P/C-G, as imaged by Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) narrow-angle camera on Tuesday, July 29. At the time just about a week away from making its arrival, ESA’s spacecraft was 1,950 km (1,211 miles) from the comet when this image was taken. (That’s about the distance between Providence, Rhode Island and Miami, Florida… that’s one fancy zoom lens, Rosetta!)
Comet 67P/Churyumov-Gerasimenko imaged on July 14, 2014 by OSIRIS from a distance of approximately 12,000 km. (ESA)
This latest image reveals some actual surface features of the 4-km-wide comet, from a few troughs and mounds to the previously-noted bright band around the “neck” connecting the two lobes. The resolution in the July 29 OSIRIS image is 37 meters per pixel.
Since Rosetta is quickly closing the gap between itself and the comet we can only expect better images to come in the days ahead, so stay tuned — this is going to be an exciting August!
Keep up with the latest news on ESA’s Rosetta blog here, and find out where exactly Rosetta and Comet 67P/C-G are in the Solar System here.
An artist's conception of the hot local bubble. Image Credit: NASA
I spent this past weekend backpacking in Rocky Mountain National Park, where although the snow-swept peaks and the dangerously close wildlife were staggering, the night sky stood in triumph. Without a fire, the stars, a few planets, and the surprisingly bright Milky Way provided the only light to guide our way.
But the night sky as seen by the human eye is relatively dark. Little visible light stretching across the cosmos from stars, nebulae, and galaxies actually reaches Earth. The entire night sky as seen by an X-ray detector, however, glows faintly.
The origins of the soft X-ray glow permeating the sky have been highly debated for the past 50 years. But new findings show that it comes from both inside and outside the Solar System.
Decades of mapping the sky in X-rays with energies around 250 electron volts — about 100 times the energy of visible light — revealed soft emission across the sky. And astronomers have long searched for its source.
At first, astronomers proposed a “local hot bubble” of gas — likely carved by a nearby supernova explosion during the past 20 million years — to explain the X-ray background. Improved measurements made it increasingly clear that the Sun resides in a region where interstellar gas is unusually sparse.
But the local bubble explanation was challenged when astronomers realized that comets were an unexpected source of soft X-rays. In fact, this process, known as solar wind charge exchange, can occur anywhere atoms interact with solar wind ions.
After this discovery, astronomers turned their eyes to within the Solar System and began to wonder whether the X-ray background might be produced by the ionized particles in the solar wind colliding with diffuse interplanetary gas.
In order to solve the outstanding mystery, a team of astronomers led by Massimilliano Galeazzi from the University of Miami developed an X-ray instrument capable of taking the necessary measurements.
Galeazzi and colleagues rebuilt, tested, calibrated, and adapted X-ray detectors originally designed by the University of Wisconsin and flown on sounding rockets in the 1970s. The mission was named DXL, for Diffuse X-ray emission from the Local Galaxy.
On Dec. 12, 2012, DXL launched from the White Sands Missile Range in New Mexico atop a NASA Black Brant IX sounding rocket. It reached a peak altitude of 160 miles and spent a total of five minutes above Earth’s atmosphere.
The data collected show that the emission is dominated by the local hot bubble, with, at most, 40 percent originating from within the Solar System.
“This is a significant discovery,” said lead author Massimiliano Galeazzi from the University of Miami in a press release. “Specifically, the existence or nonexistence of the local bubble affects our understanding of the galaxy in the proximity to the Sun and can be used as foundation for future models of the Galaxy structure.”
It’s now clear that the Solar System is currently passing through a small cloud of cold interstellar gas as it moves through the Milky Way.
Colors indicate the density of interstellar helium near Earth and its enhancement in a downstream cone as the neutral atoms respond to the sun’s gravity (blue is low density, red is high). Also shown are the observing angles for DXL and ROSAT. Image Credit: NASA’s Goddard Space Flight Center
The cloud’s neutral hydrogen and helium atoms stream through the Solar System at about 56,000 mph (90,000 km/h). The hydrogen atoms quickly ionize, but the helium atoms travel at a path largely governed by the Sun’s gravity. This creates a helium focusing cone — a breeze focused downstream from the Sun — with a much greater density of neutral atoms. These easily collide with solar wind ions and emit soft X-rays.
The confirmation of the local hot bubble is a significant development in our understanding of the interstellar medium, which is crucial for understanding star formation and galaxy evolution.
“The DXL team is an extraordinary example of cross-disciplinary science, bringing together astrophysicists, planetary scientists, and heliophysicists,” said coauthor F. Scott Porter from NASA’s Goddard Space Flight Center. “It’s unusual but very rewarding when scientists with such diverse interests come together to produce such groundbreaking results.”
Have you ever heard that spacecraft can speed themselves up by performing gravitational slingshot maneuvers? What’s involved to get yourself going faster across the Solar System.
Let’s say you want to go back in time and prevent Kirk from dying on the Enterprise B.
You could use a slingshot maneuver. You’d want to be careful that you don’t accidentally create an alternate reality future where the Earth has been assimilated by the Borg, because Kirk wasn’t in the Nexus to meet up with Professor Picard and Sir Iandalf Magnetopants, while they having the best time ever gallivanting around New York City.
*sigh* Ah, man. I really love those guys. What was I saying? Oh right. One of the best ways to increase the speed of a spacecraft is with a gravitational slingshot, also known as a gravity assist.
There are times that fantasy has bled out too far into the hive mind, and people confuse a made up thing with an actual thing because of quirky similarities, nomenclature and possibly just a lack of understanding.
So, before we go any further a “gravitational slingshot” is a gravity assist that will speed up an actual spacecraft, “slingshot maneuver” is made up bananas nonsense. For example, when Voyager was sent out into the Solar System, it used gravitational slingshots past Jupiter and Saturn to increase its velocity enough to escape the Sun’s gravity.
So how do gravitational assists work? You probably know this involves flying your spacecraft dangerously close to a massive planet. But how does this help speed you up? Sure, as the spacecraft flies towards the planet, it speeds up. But then, as it flies away, it slows down again. Sort of like a skateboarder in a half pipe.
This process nets out to zero, with no overall increase in velocity as your spacecraft falls into and out of the gravity well. So how do they do it? Here’s the trick. Each planet has an orbital speed travelling around the Sun.
As the spacecraft approaches the planet, its gravity pulls the much lighter spacecraft so that it catches up with the planet in orbit. It’s the orbital momentum from the planet which gives the spacecraft a tremendous speed boost. The closer it can fly, the more momentum it receives, and the faster it flies away from the encounter.
To kick the velocity even higher, the spacecraft can fire its rockets during the closest approach, and the high speed encounter will multiply the effect of the rockets. This speed boost comes with a cost. It’s still a transfer of momentum. The planet loses a tiny bit of orbital velocity.
If you did enough gravitational slingshots, such as several zillion zillion slingshots, you’d eventually cause the planet to crash into the Sun. You can use gravitational slingshots to decelerate by doing the whole thing backwards. You approach the planet in the opposite direction that it’s orbiting the Sun. The transfer of momentum will slow down the spacecraft a significant amount, and speed up the planet an infinitesimal amount.
Messenger’s complicated flyby trajectory. Credit: NASA
NASA’s MESSENGER spacecraft made 2 Earth flybys, 2 Venus flybys and 3 Mercury flybys before it was going slowly enough to make an orbital insertion around Mercury. Ulysses, the solar probe launched in 1990, used gravity assists to totally change its trajectory into a polar orbit above and below the Sun. And Cassini used flybys of Venus, Earth and Jupiter to reach Saturn with an efficient flight path.
Nature sure is trying to make it easy for us. Gravitational slingshots are an elegant way to slow down spacecraft, tweak their orbits into directions you could never reach any other way, or accelerate to incredible speeds.
It’s a brilliant dance using orbital mechanics to aid in our exploration of the cosmos. It’s a shining example of the genius and the ingenuity of the minds who are helping to push humanity further out into the stars.
What do you think? What other places is the general comprehension between actual facts and fictional knowledge blurring, just like the “slingshot maneuver” and “gravitational slingshot”?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
"The Chemistry of the Solar System" by Compound Interest's Andy Brunning
Here on Earth we enjoy the nitrogen-oxygen atmosphere we’ve all come to know and love with each of the approximately 24,000 breaths we take each day (not to mention the surprisingly comfortable 14.7 pounds per square inch of pressure it exerts on our bodies every moment.) But every breath we take would be impossible (or at least quickly prove to be deadly) on any of the other planets in our Solar System due to their specific compositions. The infographic above, created by UK chemistry teacher Andy Brunning for his blog Compound Interest, breaks down — graphically, that is; not chemically — the makeup of atmospheres for each of the planets. Very cool!
In addition to the main elements found in each planet’s atmosphere, Andy includes brief notes of some of the conditions present.
“Practically every other planet in our solar system can be considered to have an atmosphere, apart from perhaps the extremely thin, transient atmosphere of Mercury, with the compositions varying from planet to planet. Different conditions on different planets can also give rise to particular effects.”
– Andy Brunning, Compound Interest
And if you’re thinking “hey wait, what about Pluto?” don’t worry — Andy has included a sort of postscript graphic that breaks down Pluto’s on-again, off-again atmosphere as well. See this and more descriptions of the atmospheres of the planets on the Compound Interest blog here.
The road to a comet isn't an easy one! Luckily Rosetta and Philae have a lot of help.
…and that time is now! ESA’s Rosetta spacecraft is just over a mere two weeks away from its arrival at Comet 67P/Churyumov-Gerasimenko (which has recently surprised everyone with its binary “rubber duckie” shape) and the excitement continues to grow — and rightfully so, since after ten years traveling through the Solar System Rosetta is finally going to achieve its goal of being the first spacecraft to orbit a comet!
As part of the “Are We There Yet” campaign to encourage public participation in this historic space exploration event, ESA has released the next installment of Rosetta’s story in adorable animated format. Check it out above, and feel free to fall in love with a solar-powered spacecraft.
Keep up with Rosetta’s journey on the ESA website here, and enter the #RosettaAreWeThereYet contest by sharing your photos here (you could win a trip to ESA’s Operations Center in Darmstadt, Germany in November for Philae’s landing party!)
This artist’s view shows an extrasolar planet orbiting a star (the white spot in the right). Image Credit: IAU/M. Kornmesser/N. Risinger (skysurvey.org)
Is our Solar System normal? Or is it weird? How does the Solar System fit within the strange star systems we’ve discovered in the Milky Way so far?
With all the beautiful images that come down the pipe from Hubble, our Solar System has been left with celestial body image questions rivaling that of your average teenager. They’re questions we’re all familiar with. Is my posture crooked? Do I look pasty? Are my arms too long? Is it supposed to bulge out like this in the middle? Some of my larger asteroids are slightly asymmetrical. Can everyone tell? And of course the toughest question of all… Am I normal?
The idea that stars are suns with planets orbiting them dates back to early human history. This was generally accompanied by the idea that other planetary systems would be much like our own. It’s only in the last few decades that we’ve had real evidence of planets around other stars, known as exoplanets. The first extrasolar planet was discovered around a pulsar in 1992 and the first “hot jupiter” was discovered in 1995.
Most of the known exoplanets have been discovered by the amazing Kepler spacecraft. Kepler uses the transit method, observing stars over long periods of time to see if they dim as a planet passes in front of the star. Since then, astronomers have found more than 1700 exoplanets, and 460 stars are known to have multiple planets. Most of these stellar systems are around main sequence stars, just like the Sun. Leaving us with plenty of systems for comparison.
Artist’s impression of the solar system showing the inner planets (Mercury to Mars), the outer planets (Jupiter to Neptune) and beyond. Credit: NASA
So, is our Solar System normal? Planets in a stellar system tend to have roughly circular orbits, just like our Solar system. They have a range of larger and smaller planets, just like ours. Most of the known systems are even around G-type stars. Just like ours.….and we are even starting to find Earth-size planets in the habitable zones of their stars. JUST LIKE OURS!
Not so fast…Other stellar systems don’t seem to have the division of small rocky planets closer to the star and larger gas planets farther away. In fact, large Jupiter-type planets are generally found close to the star. This makes our solar system rather unusual.
Computer simulations of early planetary formation shows that large planets tend to move inward toward their star as they form, due to its interaction with the material of the protoplanetary disk. This would imply that large planets are often close to the star, which is what we observe. Large planets in our own system are unusually distant from the Sun because of a gravitational dance between Jupiter and Saturn that happened when our Solar System was young.
55 Cancri. Image credit: NASA/JPL
Although our Solar System is slightly unusual, there are some planetary systems that are downright quirky. There are planetary systems where the orbits are tilted at radically different angles, like Kepler 56, and a sci-fi favorite, the planets that orbit two stars like Kepler 16 and 34. There is even a planet so close to its star that its year lasts only 18 hours, known 55 Cancri e.
And so, the Kepler telescope has presented us with a wealth of exoplanets, that we can compare our beautiful Solar System to. Future telescopes such as Gaia, which was launched in 2013, TESS and PLATO slated for launch in 2017 and 2024 will likely discover even more. Perhaps even discovering the holy grail of exoplanets, a habitable planet with life…
And the who knows, maybe we’ll find another planet… just like ours.
What say you? Where should we go looking for habitable worlds in this big bad universe of ours? Tell us in the comments.
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Jupiter is like a jawbreaker. Dig down beneath the swirling clouds and you’ll pass through layer after layer of exotic forms of hydrogen. What’s down there, deep within Jupiter?
What’s inside Jupiter? Is it chameleons? Candy? Cake? Cheddar? Chemtrails? No one knows. No one can ever know.
Well, that’s not entirely true… or even remotely true. Jupiter is the largest planet in the Solar System and two and a half times the mass of the other planets combined. It’s a gas giant, like Saturn, Uranus, and Neptune. It’s almost 90% hydrogen and 10% helium, and then other trace materials, like methane, ammonia, water and some other stuff. What would be a gas on Earth behaves in very strange ways under Jupiter’s massive pressure and temperatures.
So what’s deep down inside Jupiter? What are the various layers and levels, and can I keep thinking of it like a jawbreaker? At the very center of Jupiter is its dense core. Astronomers aren’t sure if there’s a rocky region deep down inside. It’s actually possible that there’s twelve to forty five Earth masses of rocky material within the planet’s core. Now this could be rock, or hydrogen and helium under such enormous forces that it just acts that way. But you couldn’t stand on it. The temperatures are 35,000 degrees C. The pressures are incomprehensible.
Surrounding the core is a vast region made up of hydrogen. But it’s not a gas. The pressure and temperature transforms the hydrogen into an exotic form of liquid metallic hydrogen, similar to the liquid mercury you’d see in a thermometer. This metallic hydrogen region turns inside the planet, and acts like an electric dynamo. Similar to our planet’s own iron core, this gives the planet a powerful magnetic field.
The next level up is still liquid hydrogen, but the pressure’s lower, so it’s not metallic any more. And then above this is the planet’s atmosphere. The upper layers of Jupiter’s atmosphere is the only part we can see. Those bands on the planet are clouds of ammonia that rotate around the planet in alternating directions. The lighter color zones are colder ammonia ice upwelling from below. Here’s the exciting part. Astronomers aren’t sure what the darker regions are.
This animated gif shows Voyager 1’s approach to Jupiter during a period of over 60 Jupiter days in 1979. Credit: NASA.
Still think you want to descend into Jupiter, to try and walk on its rocky interior? NASA tried that. In order to protect Jupiter’s moons from contamination, NASA decided to crash the Galileo spacecraft into the planet at the end of its mission. It only got point two percent of the way down through Jupiter’s radius before it was completely destroyed.
Jupiter is a remarkably different world from our own. With all that gravity, normally lightweight hydrogen behaves in completely exotic ways. Hopefully in the future we’ll learn more about this amazing planet we share our Solar System with.
What do you think? Is there a rocky core deep down inside Jupiter?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Europa's icy, cracked surface imaged by NASA's Galileo spacecraft Credit: NASA/JPL-Caltech/SETI Institute
Eureka – it’s Europa! And a brand-new image of it, too! (Well, kinda sorta.)
The picture above, showing the icy moon’s creased and cracked surface, was made from images acquired by NASA’s Galileo spacecraft during its exploration of Jupiter and its family of moons in 1997 and 1998. While the data itself isn’t new per se the view seen here has never been released by JPL, and so it’s new to you! (And to me too.)
Europa’s bizarre surface features suggest an actively churning ice shell above a salty liquid water ocean. Credit: JPL
The original high-resolution images were acquired on Nov. 6, 1997, in greyscale and colorized with data acquired during a later pass by Galileo in 1998. The whiter areas are regions of relatively pure water ice, while the rusty red bands are where ice has mixed with salts and organic compounds that have oozed up from deeper within Europa.
The entire image area measures about 101 by 103 miles across (163 km x 167 km).
Europa has long been one of the few places we know of outside our own planet where life could very well have evolved and potentially still exist. Getting a peek below the icy moon’s frozen crust — or even a taste of the recently-discovered water vapor spraying from its south pole — is all we’d need to further narrow down the chances that somewhere, something could be thriving in Europa’s subsurface seas. Get a planetary scientist’s perspective in a video interview with Dr. Mike Brown here.
Launched in October 1989, the Galileo spacecraft arrived at Jupiter in December 1995. Through primary and extended missions Galileo explored the giant planet and its family of moons until plunging into Jupiter’s atmosphere on September 21, 2003. Learn more about Galileo here, and check out some of the amazing images it acquired on the CICLOPS imaging diary page here.
Animation of Comet 67P/Churyumov-Gerasimenko as seen by Rosetta on June 27-28, 2014
This is really getting exciting! ESA’s Rosetta spacecraft (and the piggybacked Philae lander) are in the home stretch to arrive at Comet 67P/Churyumov-Gerasimenko in 34 days and the comet is showing up quite nicely in Rosetta’s narrow-angle camera. The animation above, assembled from 36 NAC images acquired last week, shows 67P/C-G rotating over a total elapsed time of 12.4 hours. No longer just an extra-bright pixel, it looks like a thing now!
The animation, although fascinating, only hints at the “true” shape of the comet’s nucleus. Reflected light does create a bloom effect in the imaging sensor, especially at such small resolutions, expanding the apparent size of the comet beyond its 4-by-4-pixel size. But rest assured that much, much better images are on the way as Rosetta gets closer and closer.
The spacecraft was about 86,000 km (53,440 miles) from 67P/C-G when the images were acquired. Since that time it has cut that distance in half, and by this weekend it will be less than 36,000 km (22,370 miles) from the comet. After more than a decade of traveling around the inner Solar System Rosetta is finally arriving at its goal! Click here to see where Rosetta is now.
Stay tuned for more exciting updates from Rosetta, and learn more about the mission below:
