As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska
Correction, 11:33 a.m. EST: The University of Central Florida’s Phil Metzger points out that the image composition leaves out Eros, which NEAR Shoemaker landed on in 2001. This article has been corrected to reflect that and to clarify that the surfaces pictured were from “soft” landings.
And now there are eight. With Philae’s incredible landing on a comet earlier this week, humans have now done soft landings on eight solar system bodies. And that’s just in the first 57 years of space exploration. How far do you think we’ll reach in the next six decades? Let us know in the comments … if you dare.
More seriously, this amazing composition comes courtesy of two people who generously compiled images from the following missions: Rosetta/Philae (European Space Agency), Hayabusa (Japan Aerospace Exploration Agency), Apollo 17 (NASA), Venera 14 (Soviet Union), the Spirit rover (NASA) and Cassini-Huygens (NASA/ESA). Omitted is NEAR Shoemaker, which landed on Eros in 2001.
Before Philae touched down on Comet 67P/Churyumov–Gerasimenko Wednesday, the NASA Jet Propulsion Laboratory’s Mike Malaska created a cool infographic of nearly every place we’ve lived or visited before then. This week, Michiel Straathof updated the infographic to include 67P (and generously gave us permission to use it.)
And remember that these are just the SURFACES of solar system bodies that we have visited. If you include all of the places that we have flown by or taken pictures from of a distance in space, the count numbers in the dozens — especially when considering prolific imagers such as Voyager 1 and Voyager 2, which flew by multiple planets and moons.
To check out a small sampling of pictures, visit this NASA website that shows some of the best shots we’ve taken in space.
We report on the Rosetta mission to share the news and follow the progress of the precarious-perched Philae. But sometimes it takes another form of communication to dig down deep and release the wonder we all feel inside at the amazing images that daily light up our monitors. Music. Inspired by the Rosetta mission and in celebration of it, Vangelis composed three pieces of music set to slide shows featuring beautiful imagery of comet 67P/C-G and Philae. Continue reading “Music to Celebrate the Rosetta Mission”
Artist's concept of the Rosetta mission's Philae lander on the surface of comet 67P/Churyumov-Gerasimenko.
Image Credit:
ESA
This week, history was made as the Rosetta mission’s Philae lander touched down on the surface of 67P/Churnyumov-Gerasimenko. Days before this momentous event took place, the science team presented some staggering pictures of the comet at a planetary conference in Tucson, Arizona, where guests were treated to the first color images taken by the spacecraft’s high-resolution camera.
Unfortunately for millions of space enthusiasts around the world, none of these exciting images were released to the public. In addition, much of the images taken of the comet over the past few months as Rosetta closed in on it have similarly not been released. This has led to demands for more openness, which in turn has focused attention on ESA’s image and data release policy.
Allowing scientists to withhold data for some period of time is not uncommon in planetary science. According to Jim Green, the director of NASA’s Planetary Science Division, a 6-month grace period is typical for principal investigator-led spacecraft. However, NASA headquarters can also insist that the principal investigator release data for key media events.
This has certainly been the case where the Curiosity and other Mars rover missions were concerned, not to mention the Cassini-Huygens mission. On many occasions, NASA chose to release images to the public almost immediately after they were obtained.
However, ESA has a different structure than NASA. It relies much more on contributions from member-states, whereas NASA pays for most of its instruments directly. Rosetta’s main mission camera – the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) – was developed by a consortium of institutes led by the Max-Planck-Institute for Solar System Research. As a result, ESA has less control over how information obtained by this specific camera is disseminated.
The surface of comet 67P/Churyumov-Gerasimenko as viewed at a 10-kilometer distance by navigation cameras. Image Credit: ESA/Rosetta/NavCam
Journalist Eric Hand recently covered this imagery release dilemma in an article in Science, revealing that even scientists at Darmstadt, Germany this week — the location of ESA’s mission control for Philae’s landing — had not seen the science images that were being shared at the Planetary Science conference. Project scientist Matt Taylor was reduced to learning about the new results by looking at Twitter feeds on his phone.
Hand quoted Taylor as saying the decision when to publicly release images is a “tightrope” walk. And Hand also said some “ESA officials are worried that the principal investigators for the spacecraft’s 11 instruments are not releasing enough information, and many members of the international community feel the same way.”
Back in July, ESA responded to these calls for more information with a press release, in which they claimed that an “open-data” policy is not the norm for either ESA or NASA. Responding to the examples of the Mars rovers and Cassini-Huygens, which have been cited by critics for more openness, ESA countered with the Hubble Space Telescope, the Chandra X-Ray observatory, the MESSENGER mission to Mercury, and even some NASA Mars orbiters.
In these cases, they claimed, the data obtained was subject to a “proprietary period”, which also pertains to data from ESA’s Mars Express, XMM-Newton, and Rosetta missions. This period, they said, is typically 6-12 months, and “gives exclusive access to the scientists who built the instruments or to scientists who made a winning proposal to make certain observations.”
Nevertheless, there is still some criticism by those who think that releasing more images would be a positive gesture and not compromise any ESA scientist’s ability to conduct research.
As space blogger Daniel Fischer said in response to the ESA press release, “Who is writing scientific papers already about the distant nucleus that is just turning into a shape? And on the weekly schedule a sampling of these images is coming out anyway, with a few days delay… Presenting the approach images, say, one per day and with only hours delay would thus not endanger any priorities but instead give the eager public a unique chance to ‘join the ride’, just as they can with Cassini or the Mars rovers.”
The Rosetta Spacecraft’s instruments. Image Credit: ESA
In particular, a lot of criticism has been focused on the OSIRIS camera team, led by principal investigator Holger Sierks. Days before the Philae Lander put down on the comet, Stuart Atkinson – an amateur astronomer, space educator and image processor – wrote the following on his space blog Cumbrian Sky:
[The OSIRIS team’s] attitude towards the public, the media, and ESA itself has been one of arrogant contempt, and I have no doubt at all that their selfish behaviour has damaged the mission and the reputation and public image ESA. Their initial arguments that they had to keep images back to allow them to do their research no longer hold up now. They must have taken many hundreds of jaw droppingly detailed images by now, the images everyone has been looking forward to ever since ROSETTA launched a decade ago, so could easily release dozens of images which pose no risk to their work or careers, but they have released only a handful, and those have been the least-detailed, least-remarkable images they could find.
However, in Hand’s Science article, Sierks said that he feels the OSIRIS team has already provided a fair amount of data to the public. Currently, about one image is released a week – a rate that seems to Sierks to be more than adequate given that they are superior to anything before seen in terms of comet research.
Furthermore, Sierks claimed that other researchers, unaffiliated with the Rosetta team, have submitted papers based on these released images, while his team has been consumed with the daily task of planning the mission. After working on OSIRIS since 1997, Sierks feels that his team should get the first shot at using the data.
Comet 67P/Churyumov-Gerasimenko. Image Credit: ESA
This echoes ESA’s July press release, which expressed support for their science teams to have first-crack any data obtained by their instruments. “Because no-one has ever been to 67P/C-G before,” it stated, “each new piece of data from Rosetta has the potential for a scientific discovery. It’s only fair that the instrument science teams have the first chance to make and assess those discoveries.”
The same press release also defended ESA’s decision not to release information from the navigation cameras more freely – which they do have control over. Citing overlap, they indicated that they want to “avoid undermining the priority of the OSIRIS team.”
Prior to Rosetta’s launch in 2004, an embargo of 6 months was set for all the instrument teams. ESA scientists have pointed out that mission documents also stipulate that instrument teams provide “adequate support” to ESA management in its communication efforts.
Mark McCaughrean, an ESA senior science adviser at ESTEC, is one official that believes these support requirements are not being met. He was quoted by Eric Hand in Science as saying, “I believe that [the OSIRIS camera team’s support] has by no means been adequate, and they believe it has,” he says. “But they hold the images, and it’s a completely asymmetric relationship.”
A mock-up of a future Chinese Martian rover was displayed at the International Industry Fair in Shanghai (Credit: South China Morning Post)
For many space-faring nations, ambitions for Mars run broad and deep. Now, add China to the list of countries with Mars in their sights. News reports from China disclosed that country is considering a future Mars rover mission, with a potential 2020 launch date. Additionally came other hints that China may be looking to develop a next-generation heavy-lift launch system.
This new project, while early in development, reveals how Chinese aspirations are growing rapidly. Human space flight successes have been followed by recent lunar mission successes of the Yutu lunar rover and the Chang’e-5 T1 test of a sample return mission. The Chinese Mars missions could influence future plans of ESA, India and NASA or more simply raise the urgency to execute missions in concept or early development without hesitation.
China View reporter Lai Yuchen is seen describing and pointing out the future Sino-Mars rover with plans for a 2020 launch coinciding with the NASA/JPL Mars 2020 rover mission . (Click still image for video Link) (Photo/Video Credit: China View)
The Mars rover mock-up display was presented at the aerospace show by China Aerospace Science and Technology Corporation (CASC). The design appears similar to the Yutu rover which landed successfully on the Moon late in 2013. While Yutu’s mobility system failed prematurely, many mission milestones were achieved.
The Mars rover design is significantly larger than Yutu but includes changes that can be attributed to the challenges of roving Mars at tens of millions of kilometers distance and under more gravitational force. The wheels are beefed up, since it must withstand more force and rugged martian terrain (gravity on Mars is 37% of the Earth’s in strength but 2.25 times the strength of gravity on the Moon’s surface.) The the solar panels are larger due to 1.) less sunlight at Mars – 35% to 50% of Earth’s, and 2.) more electrically demanding instruments.
The goals of the Chinese Mars rover will be to search for life and water. The NASA missions searching for indicators of habitable environments and for water has cost billions of dollars but the Chinese space program is operating on a fraction of what NASA’s annual budget is. Whereas the Chinese Mars program will be competing with the lunar program for government funds, it remains to be seen how quickly they can make progress and actually meet milestones for a 2020 launch date.
Besides video of the China View reporter presenting and discussing the Mars rover (link to photo above), the video also includes a simulation of the Chinese lunar sample return spacecraft, which is underdevelopment and was tested early this month during a the Chang’e-5 T1 circum-lunar mission that proved a small re-entry vehicle.
The future Chinese rover would be nearly as large as the MER rovers. Full scale models of all three NASA/JPL Mars rovers are shown here – Mars Pathfinder, MER and MSL in a JPL Mars yard with engineers. (Photo Credit: NASA/JPL)
The actual dimensions of this rover were not reported but an estimate of the size can be determined by the size of the high-gain directional antenna. Assuming it is an X-Band dish, like the one on the MER Rovers and Curiosity, then this Sino-rover would be near the same size as the MER rovers – Spirit and Opportunity. The Sino-rover shares a six wheel design like MER and MSL rovers.
Other reports from the China Daily indicated that industry leaders in China are urging China’s space agency to develop a more powerful heavy-lift launch system. It could be used for the nation’s human spaceflight goals to send a space station in to orbit, as well as send missions to Mars and beyond.
“It is a must for us to develop a more powerful heavy-lift rocket if we want to reach and explore deep space,” Zhang Zhi, a senior rocket researcher at the China Academy of Launch Vehicle Technology the aerospace exhibition.
Plans also call for an orbiter to likely function as a communication relay as MGS, Mars Odyssey and MRO have done for the American rovers. Whether this would involve a single spacecraft such as the NASA Vikings or dual crafts such as the present American rovers with supporting orbiters is unknown. Given the successful landing of the Yutu rover encapsuled in a soft-lander, one might expect the same for the Chinese Mars rover rather than an airbag landing used by MER. Either way, they will be challenged by the seven minutes of terror just like the American rovers. They will have to solve for themselves the entry, descent and landing of a rover. Only American-made rovers have successfully landed on Mars; all Russian attempts have ended in failure.
The Chinese Lunar Sample Return mission is show in simulation in the China View video. This mission would pave the way for a Chinese Mars sample return by 2030. (Photo Credit: China View)
The presentation also stated future plans for a sample-return mission by 2030. If the first Chineses Mars rover lands successfully in 2020, it will join up to four active rovers on the surface. Curiosity, ExoMars (ESA/NASA), Mars Rover 2020 and MER Opportunity. Six years seems like a long time but MER’s Oppy is a proven trooper having lasted over ten years. Curiosity, barring the unexpected, might last beyond 2020. ExoMars and NASA’s 2020 rover are still in development phases. Using ExoMars or 2020, NASA has plans to recover collected samples from rovers and return them to Earth in the 2020s and possibly as soon as 2022.
Clouds above the rim of "Endurance Crater" in this image from NASA's Mars Exploration Rover Opportunity. These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover's 269th martian day (Oct. 26, 2004). Image Credit: NASA/JPL
Predicting the weather here on Earth is never an easy thing, but predicting it on Mars may be ever trickier. Such is the argument presented by a recent study concerning “macroweather” patterns on the Red Planet, a new regime for understanding how planetary environments work.
When it comes to describing the climate of a planet, two important concepts come into play. First, there’s weather, which covers day-to-day changes due to fluctuations in the atmosphere. Second, there’s climate, which is more stable and subject to change over the course of decades. Macroweather, the latest addition to the game, describes the relatively stable periods that exist between short-term weather and long-term climate.
For those of us dwelling here on planet Earth, these are familiar concepts. But researchers say this same three-part pattern applies to atmospheric conditions on Mars. The results of a new paper, published today in Geophysical Research Letters also show that the Sun plays a major role in determining macroweather.
Several dust devils cross a plain in this animation of a series of images acquired by NASA’s Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS)
The scientists chose to study Mars because of the wealth of data it has provided in recent decades, which they then used to test their theory that a transitional “macroweather” regime exists on a planet other than Earth. They used information collected from the Viking Mars lander mission from the 1970s and 1980s, and more recent data from the Mars Global Surveyor.
By taking into account how the sun heats Mars, as well as the thickness of the planet’s atmosphere, the scientists predicted that temperatures and wind would fluctuate on Mars similar to how they fluctuate on Earth. However, this transition from weather to macroweather would take place over 1.8 Martian days (about two Earth days), compared with a week to 10 days here on Earth.
“Our analysis of the data from Mars confirmed this prediction quite accurately,” said Shaun Lovejoy, a physics professor at McGill University in Montreal, Canada, and lead author of the paper. “This adds to evidence, from studies of Earth’s atmosphere and oceans, that the sun plays a central role in shaping the transition from short-term weather fluctuations to macroweather.”
Early Spring Dust Storms at the North Pole of Mars, taken by the Mars Global Surveyor spacecraft in 2002. Image Credit: NASA/JPL/Malin Space Science Systems
The findings also indicate that weather on Mars can be predicted with some skill only two days in advance, compared to 10 days on Earth.
“We’re going to have a very hard time predicting the weather on Mars beyond two days given what we have found in weather records there,” said co-author Jan-Peter Muller from the University College London Mullard Space Science Laboratory in the UK, “which could prove tricky for the European lander and rover.”
This research promises to advance scientists’ understanding of the dynamics of Earth’s own atmosphere, and could potentially provide insights into the weather of Venus, Saturn’s moon Titan, and possibly the gas giants Jupiter, Saturn, Uranus, and Neptune.
As always, in learning about other planets and their climates, scientists are finding that the planets of our Solar System may have more in common with Earth than previously thought. Because of this, studying these other worlds will inevitably help us to better understand our own.
Artist's conception of binary Earths. Credit: NASA
One big driver in the search for exoplanets is whether life can exist elsewhere in the Universe. In fact, a major goal of the Kepler space telescope is to discover an Earth-like planet in the habitable zone of a star like our Sun.
But what about having two Earths orbiting close to each other for billions of years? Is this even possible? A new study suggests that yes, this could happen. Imagine the implications for planetary searches if a double Earth is possible.
With current technology it’s hard to spot an Earth-sized planet, let alone resolve two, but if such planets exist it presents interesting questions. Could they be habitable? How do they form? More study is needed.
The study says double Earths can happen if they form at least half a Sun-Earth distance from their star. In what scientists say is the first-ever study considering binary Earths they suggest a scenario where two rocky bodies get close to each other early in their Solar System’s formation. They don’t collide (such as what likely formed our Moon), but they’re close enough to be within three or so radii of each other.
Artist’s conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth’s moon. Credit: NASA/JPL-Caltech
“There is a good reason to believe terrestrial binary planetary systems may be possible,” read a press release from the California Institute of Technology. “In a grazing collision the angular momentum is too high to be contained within a single rotating body (it would fission) and if the bodies barely touch then they could retain their identity. However, it requires an encounter where the bodies are initially approaching each other at low enough velocity.”
Scientists simulated these planetary encounters using a simulation, dubbed Smooth Particle Hydrodynamics, which has been used in the past for scenarios such as the collision that created the Moon. The scenarios showed that a collision between two Earth-sized planets would only produce a Moon. However, if the bodies came close enough to produce tidal distortion on each other, the planets could form a binary system.
The research was presented at the Division for Planetary Sciences meeting of the American Astronomical Society this week by undergraduate Keegan Ryan, graduate student Miki Nakajima, and planetary science researcher David Stevenson, all of the California Institute of Technology. A press release did not disclose plans for publication, or if the research is peer-reviewed.
Observations of the IC 310 radio galaxy have revealed the first lightning flashes observed from a black hole, astronomers say. Credit: Valencian Universities Network for the Promotion of Research, Development and Innovation (RUVID)
We know black holes are dangerous to people and galactic objects alike due to their immense gravity. But it turns out the galaxies that host supermassive black holes also have stormy interiors, at least according to one new study.
Scientists have found gamma-ray euptions emerging from the center of the IC 310 radio galaxy in Perseus — the strongest such variations in brightness ever found, they say — which they are comparing to a lightning storm.
It’s common for changes in brightness to happen in these galaxies as falling matter plunges into the black hole. The radio galaxies also produce jets that shoot matter away from the center at close to the speed of light.
Artist rendering of a supermassive black hole. Credit: NASA / JPL-Caltech.
What baffles researchers for IC 310 is how quickly they saw brightness shifts– on the order of five minutes, which is odd considering that the black hole’s event horizon (the point where there’s no way you’ll get out of there) requires 25 minutes to go across. This means the lightning is likely coming from a region that is smaller than the event horizon itself.
“We believe that in the black hole’s polar regions there are huge electric fields, which are able to accelerate fundamental particles at relativist speeds,” stated study leader Eduardo Ros, a researcher from the Max Planck Institute for Radio Astronomy and the Universitat de València.
“When they interact with others of lower energy, [they] are able to produce highly energized gamma rays,” he added. “We can imagine this process as a fierce electrical thunderstorm.”
Results of the study were published in the journal Science. Observatories participating included the Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes (MAGIC) at La Palma in the Canary Islands, and the European Very Large Baseline Interferometer Network.
Source: Valencian Universities Network for the Promotion of Research, Development and Innovation (RUVID)
Artist's impression of the New Horizons spacecraft. Image Credit: NASA
It’s not quite the cryogenic sleep featured in Interstellar, but all the same, NASA’s New Horizons probe has spent most of its long, long journey to Pluto in hibernation. So far it’s been asleep periodically for 1,873 days — two-thirds of its journey in space since 2006 — to save energy, money and the risk of instrument failure.
But it’s just about time for the probe to wake up. On Dec. 6, seven months before New Horizons encounters Pluto, the spacecraft will emerge from its last long nap to get ready for humanity’s first flight past the dwarf planet.
“New Horizons is healthy and cruising quietly through deep space – nearly three billion miles from home – but its rest is nearly over,” stated Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Maryland. “It’s time for New Horizons to wake up, get to work, and start making history.”
Artist’s conception of the Pluto system from the surface of one of its moons. Credit: NASA, ESA and G. Bacon (STScI)
Hibernation periods have lasted anywhere from 36 days to 202 days. Controllers usually rouse the spacecraft about twice a year to make sure all is well, and to do a little bit of science (such as taking distant pictures of Pluto of its moons). This means the next wakeup will be a new phase for the mission — a sustained effort instead of a burst of activity.
Confirmation of the wakeup should come six hours after it takes place, around 9:30 p.m. EST (2:30 p.m. UTC). This will be after the light signal takes an incredible 4.5 hours to reach Earth from New Horizons. What’s next will be a very busy few days — checking out navigation, downloading new science data, then getting the spacecraft ready for Pluto’s big closeup July 2015.
“Tops on the mission’s science list are characterizing the global geology and topography of Pluto and its large moon Charon, mapping their surface compositions and temperatures, examining Pluto’s atmospheric composition and structure, studying Pluto’s smaller moons and searching for new moons and rings,” JHUAPL stated.
First panorama sent by Philae from the surface of the comet. At upper right we see the reflection of the Sun and the top of the CONSERT instrument antenna. Credit: ESA
We may not know exactly where Philae is, but it’s doing a bang-up job sending its first photos from comet 67P/Churyumov-Gerasimenko. After bouncing three times on the surface, the lander is tilted vertically with one foot in open space in a “handstand” position. When viewing the photographs, it’s good to keep that in mind.
Philae landed nearly vertically on its side with one leg up in outer space. Here we see it in relation to the panoramic photos taken with the CIVA cameras. Credit: ESA
Although it’s difficult to say how far away the features are in the image. In an update today at a press briefing, Jean Pierre Biebring, principal investigator of CIVA/ROLIS (lander cameras), said that the features shown in the frame at lower left are about 1-meter or 3 feet away. Philae settled into its final landing spot after a harrowing first bounce that sent it flying as high as a kilometer above the comet’s surface.
After hovering for two hours, it landed a second time only to bounce back up again a short distance – this time 3 cm or about 1.5 inches. Seven minutes later it made its third and final landing. Incredibly, the little craft still functions after trampolining for hours!
Stephan Ulamec, Philae Lander manager, describes how Philae first landed less than 100 meters from the planned Agilkia site (red square). Without functioning harpoons and thrusters to fix it to the ground there, it rebounded and shot a kilometer above the comet. Right now, it’s somewhere in the blue diamond. Credit: ESA
Despite its awkward stance, Philae continues to do a surprising amount of good science. Scientists are still hoping to come up with a solution to better orientate the lander. Their time is probably limited. The craft landed in the shadow of a cliff, blocking sunlight to the solar panels used to charge its battery. Philae receives only 1.5 hours instead of the planned 6-7 hours of sunlight each day. That makes tomorrow a critical day. Our own Tim Reyes of Universe Today had this to say about Philae’s power requirements:
One of the lander’s three feet can be seen in the foreground in this high-resolution two-image mosaic. Credit: ESA/Rosetta/Philae/CIVA
“Philae must function on a small amount of stored energy upon arrival: 1000 watt-hours (equivalent of a 100 watt bulb running for 10 hours). Once that power is drained, it will produce a maximum of 8 watts of electricity from solar panels to be stored in a 130 watt-hour battery.” You can read more about Philae’s functions in Tim’s recent article.
Ever inventive, the lander team is going to try and nudge Philae into the sunlight by operating the moving instrument called MUPUS tonight. The operation is a delicate one, since too much movement could send the probe flying off the surface once again.
Here are additional photos from the press conference showing individual segments of the panorama and other aspects of Philae’s next-to-impossible landing. As you study the crags and boulders, consider how ancient this landscape is. 67P originated in the Kuiper Belt, a large reservoir of small icy bodies located just beyond Neptune, more than 4.5 billion years ago. Either through a collision with another comet or asteroid, or through gravitational interaction with other planets, it was ejected from the Belt and fell inward toward the Sun.
Astronomers have analyzed its orbit and discovered that up until 1840, the future comet 67P never came closer than 4 times Earth’s distance from the Sun, ensuring that its ices remained as pristine as the day they formed. After that date, the comet passed near Jupiter and its orbit changed to bring it within the inner Solar System. We’re seeing a relic, a piece of dirty ice rich with history. Even a Rosetta stone of its own we can use to interpret the molecular script revealing the origin and evolution of comets.
Philae falls to the craggy comet photographed by the Rosetta mothership. Credit: ESAAn image of Comet 67P/Churyumov–Gerasimenko at less than 10 km from its surface. This selection of previously unpublished ‘beauty shots’, taken by Rosetta’s navigation camera, presents the varied and dramatic terrain of this mysterious world from this close orbit phase of the mission. Credit: ESA.Frame from panoramic image. This has been heavily toned to reveal details in the shadow of the cliff. Credit: ESAFrame from panoramic image. Credit: ESAFrame from panoramic image. Credit: ESAFrame from panoramic image. Credit: ESAFrame from panoramic image. Credit: ESAImage from the Philae lander as it approached the surface. The dust-covered boulder at upper right is about 5 meters (16.4 feet) across. The dust might have originated through vaporization of ice in the boulder itself or settled there from active jets elsewhere on the comet. Credit: ESA
We’ve all heard that the Universe is expanding, but why is it expanding? What’s the force pushing everything outwards?
If still you don’t know that we live in an expanding Universe, then I’m clearly not doing my job.
And so once more, with feeling… the Universe is expanding. But that certainly doesn’t answer all the questions that go along with the it.
Like what’s the Universe expanding into? Which we did in another video, which I’ll list at the end of this episode. You might also want to know why is the Universe expanding? What’s making this happen? Did it give up its gym membership? Did it sign up for the gallon of ice cream of the month club? Has it completely embraced the blerch?
Edwin Hubble, the astronomer made famous by being named after a space telescope, provided the definitive evidence that the Universe was expanding. Observing distant galaxies, he observed they were fleeing outwards, in fact he was able to come up with calculations to show just how fast they were moving away from us.
Or to be more precise, he was able to show how fast all the galaxies are moving away from each other. Which was your question! Just like a minute ago! See you’re just as smart as Hubble!
So up until about 15 years ago, the only answer was momentum. The idea was that the Universe received all the energy it needed for its expansion in the first few moments after the Big Bang.
Imagine the beginning of the Universe, BOOM, like an explosion from a gun. And all the rest of the expansion is the Universe coasting outwards. For the longest time, astronomers were trying to figure out what this momentum would mean for the future of the Universe.
The Hubble Space Telescope image of the inner regions of the lensing cluster Abell 1689 that is 2.2 billion light?years away. Light from distant background galaxies is bent by the concentrated dark matter in the cluster (shown in the blue overlay) to produce the plethora of arcs and arclets that were in turn used to constrain dark energy. Image courtesy of NASA?ESA, Jullo (JPL), Natarajan (Yale), Kneib (LAM)
Would the mutual gravity of all the objects in the Universe cause it to slow to a halt at some point in the distant future, or maybe even collapse in on itself, leading to a Big Crunch? Or just clump up in piles and stay on the couch all summer because it’s maybe a little lazy and isn’t ready to start going back to the gym yet?
In 1999, astronomers discovered something completely unexpected… dark energy. As they were doing their observations to figure out exactly how the Universe would coast to a stop, they discovered that it’s actually speeding up. It’s as if that bullet is actually a rocket and it’s accelerating.
Now it appears that the Universe will not only expand forever, but the speed of its expansion will continue to accelerate faster and faster. So what’s causing this expansion? Currently, we believe it’s mostly momentum left over from the Big Bang, and the force of dark energy will be accelerating this expansion. Forever.
How do you feel about a rapidly accelerating expanding Universe? Tell us in the comments below.
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