Venus reflected in Boulder Lake north of Duluth, Minn. two nights ago. Credit: Bob King
Curious coincidences occur in the sky just as they do on Earth. Take tonight for instance. The moon is in gibbous phase or about 3/4 full – 78% to be exact – while Venus, which also undergoes phases identical to the moon, is likewise gibbous and 78% full.
That’s just cool. If you have telescope, focus on Venus low in the western sky just after sunset and see a perfect replica in miniature of tonight’s moon.
Look for Venus about a fist up in the west-southwest shortly after sunset. Stellarium
Be sure you’re out early as the planet is low to begin with and drops lower in the west with each passing minute. Provided the sky is haze-free, Venus isn’t difficult to spot even 5 minutes after sunset. Look about 10 degrees (one fist held at arm’s length) above the west-southwest horizon.
The moon and Venus are coincidentally in exactly the same phase tonight – 78% gibbous. Stellarium
The moon shows spectacular craters and mountains, but Venus hides its equally spectacular scenery of volcanic mountains, craters and cracked plains beneath a permanent cover of sulfur-dioxide-laced clouds. Clouds are excellent reflectors of sunlight. Not only is the planet brilliant because of them but looks as white as a shiny cue ball.
Venus’ changing position with relation to the Earth as it orbits around the sun causes it to exhibit phases like the moon. I’ve marked approximately where Venus is in mid-August. After gibbous, the planet will wane to half and then a crescent over the coming months as it catches up and passes the Earth. Illustration: Bob King
Tomorrow night the moon and Venus will go their own phase-y way, the moon fattening up toward full and Venus slowly slimming its waistline as it works its way toward the Earth. For now enjoy their temporary bond.
Like your space news, but you just can’t handle reading any more? Then watch our Weekly Space Hangout, where we give you a rundown of all the big space news stories that broke this week.
Host: Fraser Cain
Panel: Brian Koberlein, David Dickinson, Nancy Atkinson, Nicole Gugliucci
We record the Weekly Space Hangout every Friday at 12 pm Pacific / 3 pm Eastern as a live Google+ Hangout on Air. Join us live on YouTube, or you can listen to the audio after the fact on the 365 Days of Astronomy Podcast.
Area 51 shows up in Google Earth. Via Google Maps.
The CIA has released a 355-page document which officially acknowledges that Area 51 in Nevada does exist, and the agency comes clean about their weather balloon cover stories. The document covers the U-2 and SR-71 spyplane programs and Project OXCART, the aerial reconnaissance programs, from 1954 to 1974.
Nope, no revelations about extraterrestrial spacecraft or alien bodies hidden at the base, but a really grainy map showing the location of Area 51 is included.
While Area 51 has been the subject of fascination for conspiracy theorists and paranormal enthusiasts — and is entrenched in UFO-ology and pop culture — the newly declassified information (with surprisingly few redactions) admits the base was a top-secret aircraft testing facility for Cold War reconnaissance of the Soviet Union.
That UFO sightings increased during the times of the flight tests was an unexpected side effect, the document says:
High-altitude testing of the U-2 soon led to an unexpected side effect-a tremendous increase in reports of unidentified flying objects (UFOs). In the mid-1950s, most commercial airliners flew at altitudes between 10,000 and 20,000 feet and military aircraft like the B-47s and B-57s operated at altitudes below 40,000 feet. Consequently once U-2s started flying at altitudes above 60,000 feet, air-traffic controllers began receiving increasing numbers of UFO reports.
The document also explains Project Blue Book and other frequently associated UFO story staples. The job of Project Blue Book was actually to figure out when civilians were reporting UFOs that were actually U-2s and then work out how to keep that from happening again.
Why did people on the ground and even other pilots report “shiny” UFOs? The document explains that the U-2s silver wings were at the right altitude that when the ground below, or even planes flying at a lower altitude were in darkness, the U-2 was in sunlight and its silver wings would glint in the sunlight:
Such reports were most prevalent in the early evening hours from pilots of airliners flying from east to west. When the sun dropped below the horizon of an airliner flying at 20,000 feet. the plane was in darkness. But, if a U-2 was airborne in the vicinity of the airliner at the same its horizon from an altitude of 60,000 feet was considerably more distant, and being so high in the sky, its silver wings would catch and reflect the ray of the sun and appear to the airliner pilot 40,000 feet below to be fiery objects. Even during the daylight hours, the silver bodies of the high-flying U-2s could catch the sun and cause reflections or glints that could be seen at lower altitudes and even on the ground. At this time, no one believed manned flight was possible above 60,000 feet, so no one expected to see an object so high in the sky.
A handwritten document about the U-2 spyplane design that was included in the information released by the CIA about test flights and Area 51.
But then, not all the UFO reports were explained by U-2 flights.
Air Force investigators then attempted to explain such sightings by linking them to natural phenomena. BLUE BOOK investigators regularly called on the Agency’s Project Staff in Washington to check reported UFO sightings against U-2 flight logs. This enabled the investigators to eliminate the majority of the UFO reports, although they could not reveal to the letter writers the true cause of the UFO sightings. U-2 and later OXCART flights accounted for more than one-half of all UFO reports during the late 1950s and most of the 1960s.
In the document, the CIA admits the weather balloon stuff was just a cover story, but it was the standard operating procedure for how to explain away the sightings as well as debris from any crashes. However, this cover story ended up having disastrous results in May of 1960 when the crash of a U-2 in Russia and the subsequent capture of pilot Gary Powers set in motion a pattern of mistrust between the US and USSR that culminated in the Cuban Missile Crisis in 1962.
After the plane and the pilot went missing, and with the fate of the plane and pilot unknown, the CIA had NASA release a statement that they had a weather airplane that went off course over the Soviet Union because the pilot had passed out due to a loss of oxygen. That story was quickly proven to be a hoax when the USSR produced the crashed U-2 plane and the pilot, who survived the crash and who had admitted to spying.
The documents were released in response to a Freedom of Information Act request submitted in 2005 by Jeffrey T. Richelson, a senior fellow at the National Security Archives. Originally, the CIA had released a heavily redacted document with all mention of Area 51 blacked out. This new document reveals pretty much everything except names of military personnel and private citizens involved.
Richelson has pointed out that the location of Area 51 was not a particularly well-kept secret. Its location appears in satellite imagery like Google Maps and Google Earth, as well as in books on aerial surveillance.
You can wade through the 355 page document here. If you enjoy military and aircraft history, its a great read. One interesting fact revealed is that President Eisenhower wanted the pilots of these planes to be non-US citizens. “It was his belief that, should a U-2 come down in hostile territory, it would be much easier for the United States to deny any responsibility for the activity if the pilot was not an American,” the document reports.
And while I have this chance, I’m going to share a great graphic going around Twitter on how to identify any strange light in the sky you may see:
If you go out hiking this weekend and somehow find yourself hopelessly lost in the wilderness, but suddenly remember you have a compass with you, you can use it to find north because the needle always points towards the Earth’s geographic north pole, which never changes… right?
Wrong, wrong, and wrong. And this video from MinutePhysics explains why.
(But still bring a compass with you. They do come in handy.)
Sierra Nevada Corp.'s Dream Chaser just before tow tests at NASA's Dryden Flight Research Center on Aug. 2, 2013. Credit: NASA/Ken Ulbrich
Another kind of commercial spacecraft is almost ready to take flight, its backers say.
Sierra Nevada Corp.’s Dream Chaser recently finished four low- and high-speed ground tests at NASA’s Dryden Flight Research Center in Edwards, Calif., the same spot where the shuttle was put through its paces in early tests of its program. Several shuttle flights also landed at Dryden.
The Dream Chaser tow-and-release tests, which took place at speeds ranging from 10 to 60 miles per hour (16 to 96 kilometers per hour), examined items such as the flight computer, how the guidance performed, steering parameters and the flight surfaces.
“Watching Dream Chaser undergo tow testing on the same runway where we landed several space shuttle orbiters brings a great amount of pride to our Dream Chaser team,” stated Steve Lindsey, SNC’s Space Systems senior director of programs, who is also a former NASA astronaut.
“We are another step closer to restoring America’s capability to return U.S. astronauts to the International Space Station.”
The next step will be an approach and landing test, which should take place sometime in the third quarter of 2013.
SNC is one of three companies receiving money from NASA under the agency’s commercial crew program, whose goal is to move astronaut launches back to American soil in the next few years. The other competitors are SpaceX and Boeing. You can read a more in-depth look at their proposals here.
An artist's conception of two neutron stars, moments before they collide. Image Credit: NASA
The Universe is sizzling with undiscovered phenomena. Only last month astronomers heard four unexpected bumps in the night. These Fast Radio Bursts released torrents of energy, each occurred only once, and lasted a few thousandths of a second. Their origin has since mystified astronomers.
Dismissing my first guess, which includes a feverish Jodie Foster verifying the existence of extraterrestrial life, astronomers have found a more likely answer. Two neutron stars collide, but before doing so produce a quick burst of radio emission, which we later observe as a Fast Radio Burst.
Our first hint? These Fast Radio Bursts are extra-galactic in origin. The exact distance is quantifiable from a “dispersion measure – the frequency dependent time delay of the radio signal,” Dr. Tomonori Totani, lead author on the paper, told Universe Today. “This is proportional to the number of electrons along the line of sight.”
For all bursts, the short-wavelength component arrived at the telescope a fraction of a second before the longer wavelengths. This is due to an effect known as interstellar dispersion: through any medium, longer-wavelength light moves slightly slower than short-wavelength light.
Light from extra-galactic objects will have to travel through intergalactic space, which is teeming with electrons in clouds of cold plasma. The farther the light travels, the more electrons it will have to travel through, and the greater the time delay between arriving wavelength components. By the time light reaches the Earth, it has been dispersed, and the amount of dispersion is directly correlated with distance.
These Fast Radio Bursts are likely to have originated anywhere from 5 to 10 billion light years away.
While the exact source of these Fast Radio Bursts has been highly debated, a recent hypothesis concludes that they are the result of merging neutron stars in the distant Universe.
In the final milliseconds before merging, the rotation periods of the two neutron stars synchronize – they become tidally locked to one another as the Moon is tidally locked to the Earth. At this point their magnetic fields also synchronize. Energetic charged particles spiral along the strong magnetic field lines and emit a beam of radio synchrotron emission.
Known neutron star magnetic field strengths are consistent with the radio flux observed in these Fast Radio Bursts. The emission then ceases in a few milliseconds when the two neutron stars have collided, which explains the short duration of these Fast Radio Bursts.
Not only does this mechanism describe both the high energy and the time duration of these bursts, but they’re inferred occurrence rate as well. It’s likely that 100,000 Fast Radio Bursts occur each day. This matches the likely neutron star merger rate.
Merging neutrons stars will also create gravitational waves – ripples in the curvature of spacetime that propagate away from the event. Dr. Totani emphasized that the next step will be to perform a correlated search of gravitational waves and Fast Radio Bursts. Such a fast rate estimate is certainly good news for scientists hoping to detect gravitational waves in the nearby future.
The Universe is bursting with energy – literally – every 10 seconds, and until recently we simply had no idea. This recently discovered phenomenon is likely to be the center of a new active area of research. And I have no doubt that it will lead to exciting discoveries that just may break trends and burst into new territories.
The discovery paper may be found here, while the paper analyzing neutron stars as a likely source may be found here.
During the stationary recovery test of Orion at Norfolk Naval Base on Aug. 15, US Navy divers attached tow lines and led the test capsule to a flooded well deck on the USS Arlington. Credit: Ken Kremer/kenkremer.com
During the stationary recovery test of Orion at Norfolk Naval Base on Aug. 15, 2013, US Navy divers attached tow lines and led the test capsule to a flooded well deck on the USS Arlington. Credit: Ken Kremer/kenkremer.com. Story updated with additional test Video and images[/caption]
NAVAL STATION NORFOLK,VA – When American astronauts again venture into deep space sometime in the next decade, their return trip to Mother Earth will end with the splashdown of their Orion capsule in the Pacific Ocean – much like the Apollo lunar landing crews of four decades ago.
But before that can happen, Orion must first pass through a myriad of milestones to insure the safe return of our human crews.
A NASA and U.S. Navy test successfully demonstrated the water recovery of the Orion crew module today (Aug. 15) at Naval Station Norfolk in Virginia – and Universe Today witnessed the entire operation.
“Today’s test was terrific,” Scott Wilson, NASA’s Orion Manager of Production Operations, told Universe Today in a post test interview at Naval Station Norfolk.
“We got all the data we needed and the test was very successful. This was exactly what we wanted to do and we don’t like surprises.”
US Navy divers on four boats attached tow lines and to the Orion test capsule and guide it to the well deck on the USS Arlington during Aug. 15 recovery test at Norfolk Naval Base, VA.
Credit: Ken Kremer/kenkremer.com
Today’s ‘Orion Stationary Recovery Test’ was conducted to support the upcoming first flight of Orion on the EFT-1 mission due to blastoff in September 2014 from Cape Canaveral, Florida.
“We completed all of our primary and secondary test objectives,” Wilson stated.
Teams of US Navy divers in a flotilla of amphibious boats launched from the USS Arlington approached a test version of the Orion capsule known as the boilerplate test article (BTA). The Arlington was docked against its pier during the test in a benign, controlled environment.
Dive teams attach tow lines to Orion test capsule during Aug. 15 recovery test at Norfolk Naval Base, VA. Credit: Ken Kremer/kenkremer.com
Divers attached several tow lines to the capsule, in a coordinated operation with the Arlington, and led the capsule into the ship’s flooded well deck.
The Orion capsule was carefully towed inside the well deck and positioned over the recovery cradle. The sea water was drained and the capsule was attached to the recovery cradle.
Dive teams haul Orion onto the well deck of the USS Arlington during Aug. 15 recovery test at Norfolk Naval Base, VA. Credit: Ken Kremer/kenkremer.com
“During the test there is constant radio communications between the ship and the divers teams in the boats.”
“The operation within the well deck areas are also being controlled as well as the rope and winch handlers on the boat,” Wilson told me.
At the conclusion of the test, myself and the NASA social media participants boarded the USS Arlington and toured the Orion capsule for a thrilling up close look.
Myself and NASA social media participants observed Orion after hauled aboard the well deck and boarded the USS Arlington recovery ship. Credit: Ken Kremer/kenkremer.com
“Today marks a significant milestone in the Navy’s partnership with NASA and the Orion Human Space Flight Program,” said Navy Commander Brett Moyes, Future Plans Branch chief, U.S. Fleet in a statement.
“The Navy is excited to support NASA’s continuing mission of space exploration. Our unique capabilities make us an ideal partner for NASA in the recovery of astronauts in the 21st century — just as we did nearly a half century ago in support of America’s quest to put a man on the moon.”
The ocean recovery of Orion will be far different from the Apollo era where the crew’s were first hoisted out of the floating capsule and the capsule then hoisted on deck of a US Navy aircraft carrier.
The next Orion water recovery test will be conducted in the open waters of the Pacific Ocean in January 2014.
Inside up close look at the Orion attached to the recovery cradle in the drained well deck of the USS Arlington recovery ship. Credit: Ken Kremer/kenkremer.com
NASA’s Langley Research Center in nearby Hampton, VA is conducting an extensive drop test program in support of the Orion project.
“The Orion capsule tested today has the same mold line and dimensions as the Orion EFT-1 capsule.”
“The Orion hardware and the Delta IV Heavy booster for the EFT-1 launch are on target for launch in 2014,” Wilson told me.
Watch this NASA Video of the Orion test:
During the unmanned Orion EFT-1 mission, the capsule will fly on a two orbit test flight to an altitude of 3,600 miles above Earth’s surface, farther than any human spacecraft has gone in 40 years.
The EFT-1 mission will provide engineers with critical data about Orion’s heat shield, flight systems and capabilities to validate designs of the spacecraft before it begins carrying humans to new destinations in the solar system, including an asteroid and Mars.
It will return to Earth at a speed of approximately 20,000 mph for a splashdown in the Pacific Ocean.
Right now its T Minus 1 Year and counting to liftoff of Orion EFT-1.
…………….
Learn more about Orion, Cygnus, Antares, LADEE, MAVEN, Mars rovers and more at Ken’s upcoming presentations
Sep 5/6/16/17: LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
Social media and media including Ken observe the Aug. 15 Orion water recovery test from the pier at Naval Station Norfolk, VA. Credit: NASAScott Wilson, NASA’s Orion production manager and Ken Kremer, Universe Today discuss the Aug. 15 recovery test back dropped by Orion and the USS Arlington. Credit: Ken Kremer/kenkremer.com
Has Voyager 1 actually left the Solar System? Some researchers are saying yes. (Image: NASA/JPL-Caltech)
Nearly 18.7 billion kilometers from Earth — about 17 light-hours away — NASA’s Voyager 1 spacecraft is just about on the verge of entering interstellar space, a wild and unexplored territory of high-energy cosmic particles into which no human-made object has ever ventured. Launched in September 1977, Voyager 1 will soon become the first spacecraft to officially leave the Solar System.
Or has it already left?
I won’t pretend I haven’t heard it before: Voyager 1 has left the Solar System! Usually followed soon after by: um, no it hasn’t. And while it might all seem like an awful lot of flip-flopping by supposedly-respectable scientists, the reality is there’s not a clear boundary that defines the outer limits of our Solar System. It’s not as simple as Voyager rolling over a certain mileage, cruising past a planetary orbit, or breaking through some kind of discernible forcefield with a satisfying “pop.” (Although that would be cool.)
The outer edge of the heliosphere has been found to contain many different regions, which Voyager 1 has been passing through since 2004. (NASA/JPL-Caltech)
Rather, scientists look at Voyager’s data for evidence of a shift in the type of particles detected. Within the transitionary zone that the spacecraft has most recently been traveling through, low-energy particles from the Sun are outnumbered by higher-energy particles zipping through interstellar space, also called the local interstellar medium (LISM). Voyager’s instruments have been detecting dramatic shifts in the concentrations of each for over a year now, unmistakably trending toward the high-energy end — or at least showing a severe drop-off in solar particles — and researchers from the University of Maryland are claiming that this, along with their model of a porous solar magnetic field, indicates Voyager has broken on through to the other side.
“It’s a somewhat controversial view, but we think Voyager has finally left the Solar System, and is truly beginning its travels through the Milky Way,” said Marc Swisdak, UMD research scientist and lead author of a new paper published this week in The Astrophysical Journal Letters.
According to Swisdak, fellow UMD plasma physicist James F. Drake, and Merav Opher of Boston University, their model of the outer edge of the Solar System fits recent Voyager 1 observations — both expected and unexpected. In fact, the UMD-led team says that Voyager passed the outer boundary of the Sun’s magnetic influence, aka the heliopause… last year.
But, like some of last year’s claims, these conclusions aren’t shared by mission scientists at NASA.
“Details of a new model have just been published that lead the scientists who created the model to argue that NASA’s Voyager 1 spacecraft data can be consistent with entering interstellar space in 2012,” said Ed Stone, Voyager project scientist at Caltech, in a press release issued today. “In describing on a fine scale how magnetic field lines from the sun and magnetic field lines from interstellar space can connect to each other, they conclude Voyager 1 has been detecting the interstellar magnetic field since July 27, 2012. Their model would mean that the interstellar magnetic field direction is the same as that which originates from our sun.
The famous “Golden Record” carried aboard both Voyager 1 and 2 contains images, sounds and greetings from Earth. (NASA)
“Other models envision the interstellar magnetic field draped around our solar bubble and predict that the direction of the interstellar magnetic field is different from the solar magnetic field inside. By that interpretation, Voyager 1 would still be inside our solar bubble.”
Stone says that further discussion and investigation will be needed to “reconcile what may be happening on a fine scale with what happens on a larger scale.”
Whether still within the Solar System — however it’s defined — or outside of it, the bottom line is that the venerable Voyager spacecraft are still conducting groundbreaking research of our cosmic neighborhood, 36 years after their respective launches and long after their last views of the planets. And that’s something nobody can argue about.
“The Voyager 1 spacecraft is exploring a region no spacecraft has ever been to before. We will continue to look for any further developments over the coming months and years as Voyager explores an uncharted frontier.”
– Ed Stone, Voyager project scientist
Built by JPL and launched in 1977, both Voyagers are still capable of returning scientific data from a full range of instruments, with adequate power and propellant to remain operating until 2020.
Note: The definition of “Solar System” used in this article is in reference to the Sun’s magnetic influence, the heliosphere, and all that falls within its outermost boundary, the heliopause (wherever that is.) Objects farther out are still gravitationally held by the Sun, such as distant KBOs and Oort Cloud comets, but orbit within the interstellar medium.
Screen grab from Michael K. Chung's timelapse of a Perseid meteor exploding.
Personally, I’ve never seen anything like this, and photographer and digital artist Michael K. Chung said he couldn’t believe what he saw when he was processing images he took for a timelapse of the Perseid meteor shower. It appears he captured a meteor explosion and the resulting expansion of a shock wave or debris ring.
“It was taken early in the morning on August 12, 2013 from my backyard in Victorville, CA,” Michael told Universe Today via email. “The fade to white is NOT an edit- it is overexposure due to the sun coming up. From what I can tell, the timelapse sequence of the explosion and expanding debris span an actual time of approximately 20 minutes.”
Michael said because he shoots at much higher resolution than 720p, he’s able to provide two different sequences in this video: one is with the full frame of each capture scaled/reduced and then cropped down to 1280×720, and the other is with the full frame kept at resolution with just the region around the explosion cropped to 1280×720. “I included each sequence twice – once at 24 frames per second and the other at around 12 fps.”
Amazing!
Since I’ve never seen anything like this, I decided to have one of our observing experts provide his opinion. UT writer David Dickinson said this is definitely legitimate.
“What cinches it for me is that the meteor was moving in the right direction for a Perseid,” Dave told me. “I see Perseus rising to the right, the plane of the Milky Way and Andromeda just above center.”
Dave said he has seen several meteors that leave lingering smoke trains. “I usually carry binoculars to examine these,” he said, “and saw several examples of this during the 1998 Leonid meteor storm from the desert in Kuwait, one of the most awesome things I’ve seen. Ever.”
Dave concurs, great catch by Michael Chung!
Update:Daniel Fischer provided a link to some imagery and information of the 1998 Leonid observations, showing persistent trains and more. Daniel also provided a more accurate description of what Michael Chung captured: “a persistent train after a Perseids fireball, being torn apart by upper atmosphere wind shear.”
Second update:
We heard from a few more people who also witnessed and captured similar Perseids with persistent trains.
Steve Knight from the UK also captured some explody-Perseids this year. Take a look at his video below, and at :15 and :19 there are fireballs followed by expanding cloud of debris — to see it better expand the video and look at the top right part of the screen. Andromeda Galaxy (M31) is visible drifting in from the left.
And Steve also provided animated gifs of the explosions:
Also, Randy Halverson from Dakotalapse, whose work we feature frequently on UT sent a couple of images of persistent trains from meteors, like this one:
Meteor with persistent train, taken on October 6th, 2012, from the same spot a similar image was taken a year earlier. Credit and copyright: Randy Halverson/dakotalapse.
…and this one of the cloud of debris left from a persistent train:
Cloud of debris from a meteor explosion seen near the White River in South Dakota on October 1, 2011. Credit and copyright: Randy Halverson/dakotalapse.
Watch his timelapse here, with the explosion taking place at about :53 into the film:
… with an interesting story that he set up his equipment to do a timelapse in the same place two years in a row and captured persistent trains both years. To find out more about that, as well as get more info on persistent trains, Phil Plait wrote this article about it.
There’s also an animated gif of an exploding Perseid from astromel on Flickr here.
This image was taken by the Curiosity rover's right Mastcamy on Sol 351 (2013-08-01 08:44:11 UTC). Image Credit: NASA/JPL-Caltech/MSSS.
Sol 351 for the Curiosity rover on Mars was a marvelous night for a moon dance. The Mars Science Laboratory rover caught sight of Mars’ two moons, Phobos and Deimos together in the sky. And not just one image was captured: the rover’s Mast Camera captured a series of 41 images to allow the MSL team to create this timelapse movie of the dance, where the smaller moon Diemos is occulted by Phobos.
The movie from MSL takes just a few seconds to watch, but the team said the real time it took to shoot the 41 images was 55 seconds.
Sol 351 equates to August 1, 2013 here on Earth.
See a raw still shot below:
Update: JPL has now put out a press release about the movie, confirming that no previous images from missions on the surface has caught one moon eclipsing the other.
They also said there was a slight delay in getting these images from the rover, as there were higher-priority images in the queue that were to be used for planning the rover’s drives.
Scientists know that the orbit of Phobos is very slowly getting closer to Mars, while the orbit of Deimos may be slowly getting farther from the planet. These observations of Phobos and Deimos help researchers make knowledge of the moons’ orbits even more precise.
“The ultimate goal is to improve orbit knowledge enough that we can improve the measurement of the tides Phobos raises on the Martian solid surface, giving knowledge of the Martian interior,” said Mark Lemmon of Texas A&M University, College Station, a co-investigator for use of Curiosity’s Mastcam. “We may also get data good enough to detect density variations within Phobos and to determine if Deimos’ orbit is systematically changing.”
There’s also this nice graphic comparing our Moon to Phobos and Deimos:
his illustration provides a comparison for how big the moons of Mars appear to be, as seen from the surface of Mars, in relation to the size that Earth’s moon appears to be when seen from the surface of Earth. Earth’s moon actually has a diameter more than 100 times greater than the larger Martian moon, Phobos. However, the Martian moons orbit much closer to their planet than the distance between Earth and Earth’s moon. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.
Although Phobos has a diameter less than one percent the diameter of Earth’s Moon, Phobos also orbits much closer to Mars than our moon’s distance from Earth. As seen from the surface of Mars, Phobos looks about half as wide as what Earth’s moon looks like to viewers on Earth.
