The Subaru Telescope. Credit: National Astronomical Observatory of Japan
Put another checkmark beside the “cold dark matter” theory. New observations by Japan’s Subaru Telescope are helping astronomers get a grip on the density of dark matter, this mysterious substance that pervades the universe.
We can’t see dark matter, which makes up an estimated 85 percent of the universe, but scientists can certainly measure its gravitational effects on galaxies, stars and other celestial residents. Particle physicists also are on the hunt for a “dark matter” particle — with some interesting results released a few weeks ago.
The latest experiment with Subaru measured 50 clusters of galaxies and found that the density of dark matter is largest in the center of these clusters, and smallest on the outskirts. These measurements are a close match to what is predicted by cold dark matter theory, scientists said.
Cold dark matter assumes that this material can’t be observed in any part of the electromagnetic spectrum, the band of light waves that ranges from high-energy X-rays to low-energy infrared heat. Also, the theory dictates that dark matter is made up of slow-moving particles that, because they collide with each other infrequently, are cold. So, the only way dark matter interacts with other particles is by gravity, scientists have said.
To check this out, Subaru peered at “gravitational lensing” in the sky — areas where the light of background objects are bent around dense, massive objects in front. Galaxy clusters are a prime example of these super-dense areas.
Several dark matter maps: one based on a sample of 50 individual galaxy clusters (left), another looking at an average galaxy cluster (center), and another based on dark matter theory (right). Red is the highest concentration of dark matter, followed by yellow, green and blue. At right, in the middle, is a map based on cold dark matter theory that comes close to the average galaxy cluster observed with the Suburu Telescope. Credit: NAOJ/ASIAA/School of Physics and Astronomy, University of Birmingham/Kavli IPMU/Astronomical Institute, Tohoku University)
“The Subaru Telescope is a fantastic instrument for gravitational lensing measurements. It allows us to measure very precisely how the dark matter in galaxy clusters distorts light from distant galaxies and gauge tiny changes in the appearance of a huge number of faint galaxies,” stated Nobuhiro Okabe, an astronomer at Academia Sinica in Taiwan who led the study.
Next, the team members could compare where the matter was most dense with that predicted by cold dark matter theory. To do that, they measured 50 of the most massive, known clusters of galaxies. Then, they measured the “concentration parameter”, or the cluster’s average density.
“They found that the density of dark matter increases from the edges to the center of the cluster, and that the concentration parameter of galaxy clusters in the near universe aligns with CDM theory,” stated the National Astronomical Observatory of Japan.
The next step, researchers stated, is to measure dark matter density in the center of the galaxy clusters. This could reveal more about how this substance behaves. Check out more about this study in Astrophysical Journal Letters.
Chris Lewicki in the clean room. His role as flight director for the two MER rovers and surface operations manager for the Phoenix mission required an intimate knowledge of all the spacecraft systems. Image courtesy Chris Lewicki.
Chris Lewicki is the President and Chief Engineer for one of the most pioneering and audacious companies in the world today. Planetary Resources was founded in 2008 by two leading space advocates, Peter Diamandis, Chairman and CEO of the X-Prize Foundation and Eric Anderson, a forerunner in the field of space tourism. In from the earliest days of the company, in turning to Lewicki, Anderson and Diamandis have gained scientific and management expertise which reaches far beyond low Earth orbit.
Chris is a recipient of two NASA Exceptional Achievement Medals and has an asteroid name in his honour, 13609 Lewicki. Chris holds bachelor’s and master’s degrees in Aerospace Engineering from the University of Arizona.
In this exclusive interview with Nick Howes, Lewicki gives us a feel for what lies behind Planetary Resources most compelling step yet in their quest to bring space to the masses.
Chris Lewicki is the President and Chief Engineer for Planetary Resources, Inc. Image courtesy Planetary Resources.
Nick Howes – So Chris, what first inspired you to get in to astronomy and space science?
Chris Lewicki – So, I guess it wasn’t a person as most would say, but a mission that got me started on this road. Even before college, and you have to remember I grew up in dairy country in Northern Wisconsin, where we didn’t really have much in the way of space. I wanted to do something interesting, and found I was good at math. When I saw the Voyager 2 spacecraft flyby of Neptune and Triton, I thought “wow this is it,” and wanted to work at JPL pretty much from that moment onwards. Thinking that this was a “really special place.”
Voyager 2’s encounter with Nepture. Credit: NASA
NH – At college were you determined to work for someone like NASA, and was your time at Blastoff a good stepping stone in to this?
CL – I think it really did start even before college, like I said, from the Voyager 2 encounter and all the subsequent missions which JPL were involved in this was kind of the goal. Ahead of JPL though, was my first encounter with Peter (Diamandis) and Eric (Anderson) when we worked on starport.com where I was a web developer. Prior to that I’d had a spell at the Goddard Space Flight Centre, but with Eric and Peter, we really did form a bond. Starport didn’t last too long though, as it was at the time of the dotcom boom and bubble, but it taught me some valuable lessons in those months.
Then I took up a position at JPL, but as you probably know, not everything they do is mission design and planning, and while it is an amazing place, I wanted to get my hands on some real mission stuff, so moved on after just under a year.
Then came Blastoff which kind of set a lot of the wheels in motion for ideas relating to the Google Lunar X-Prize. We had a lot of fun there designing rovers and exploratory missions to the Moon, lots of great people with great ideas.
I was then at a small satellites conference in Utah, when a representative of JPL came up to me after my talk, gave me his business card and effectively said I should come and do an interview for them. Peter and Eric didn’t really want me to go, but I told them “I really have to go off and learn how to build rockets.” Thus really started the real journey working with NASA on some of the most exciting missions in recent history.
NH – How thrilling was it being the flight director for two of the most successful missions in NASA’s history?
A view of the Flight Control room at the Jet Propulsion Laboratory during the landing of the Spirit Mars Exploration Rover, Spirit, with Chris in the Flight Director hotseat. Credit: NASA/JPL.
CL – Thrilling really doesn’t come close to covering it. There I was, 29 years old, thinking “should I really be doing this?” but then, realising “yes, I can do this” sitting in the flight directors desk for two of NASA’s most audacious missions, being Spirit and Opportunity. It was my role to get them safely down on the surface, and boy did we test those missions.
The simulators were so realistic; we’d be running so many different scenarios for years prior to the actual EDL phase, now known as the “7 minutes of terror”. It really doesn’t feel quite real though when it’s actually happening, you just know it is because the room is full of TV cameras, and you have that extra notion in the back of your mind saying it’s not a sim this time. The telemetry though in the simulations was so close to the real data, just a few variations, it kind of showed how much testing and planning went in to those missions, and how it all paid off.
NH – With Phoenix you’d obviously experienced the sadness of the loss of Polar Lander before hand; did that teach you any valuable lessons which you have now carried forward to your role at Planetary Resources?
CL – Phoenix started with a failure review, but that’s what I think is so important about engineering and indeed life in general. You have to fail to understand how to make things better. During that design review we figured out a dozen more reasons for things that could have gone wrong with Mars Polar Lander, and implemented the changes for Phoenix. You have to plan for failure so much with missions of this type, and it’s quite an exhilarating but in some ways stressful ride, and one that after Phoenix I felt like I needed to pass the mantle on to for Curiosity.
NH – On the topic of Planetary Resources, when did you start to think about being part of a company of this magnitude?
Artist concept of the ARKYD spacecraft by an asteroid. Credit: Planetary Resources.
CL – Well working with Peter and Eric again was mooted as long ago as 2008, the company ideas being formulated then when it was called Arkyd Astronautics, a name which stuck with us until 2012. Eric and Peter approached me about possibly coming back. As I said, I’d pretty much resigned myself to not working on Curiosity, and having to put myself through all of the phases associated with that landing, and there’s a quote which many people believe comes from Mark Twain, but is really from Jackson Brown, that basically says
“Twenty years from now you will be more disappointed by the things that you didn’t do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover” I decided to throw off the bowlines and set sail with Planetary Resources.
NH – How do you see your relationship with a company like Planetary Resources with the major space agencies? Do you see yourselves as complimenting them or competing?
CL – Complimenting totally. NASA has over 50 years of incredible exploration, missions, research, development and insight, and a great future ahead of them too. With NASA recently transferring some of their low Earth orbit operations in to the commercial sector, we feel that this is really a great time to be in this industry, with our goals for being at the forefront of the types of science and commercial operations that the business sector can excel in, leaving NASA to focus on the amazing deep space missions, like landing on Europa or going back to Titan, missions like that, which only the large government agencies can really pull off at this time.
NH – The Arkyd has to be one of the most staggering Kickstarter success stories ever, raising aaround $800,000 in a week…did you imagine that the reaction to putting a space telescope available for all in to orbit would garner so much enthusiasm?
Artist concept of the ARKYD telescope in space. Credit: Planetary Resources.
CL – Staggering again doesn’t really do it enough justice. This is the biggest space based Kickstarter in their history, as it’s also in the photography category; it’s the biggest photographic Kickstarter ever too. We have many more surprises planned which I can’t go in to now, but in setting the $1 million minimum bar to “test the water” with public interest in a space telescope, we’ve not really exceeded expectations, but absolutely reached what we felt was possible. From talking to people ahead of the launch, and just seeing their reaction (note from author, I was one of those people, and my reaction was jaw dropping) we knew we had something really special. The idea of the space selfie we felt was part of the cornerstone of what we wanted to achieve, opening up space to everyone, not just the real die hard space enthusiasts.
NH – With the huge initial success of the Arkyd project, do you see any scope for a flotilla of space telescopes for the public, much like say the LCOGT or iTelescope networks are on Earth?
CL – Possibly in the future. You yourself know with your work with the Las Cumbres and Faulkes network and iTelescope networks that having a suite of telescopes around the planet has huge benefits when it comes to observations and science. At present we have the plan for one telescope for public use as you know.
The Arkyd 100, which will be utilising our Arkyd technologies, which we’ll be using to examine near Earth asteroids. If you think, that in the last 100 years, the Hale’s, Lowell’s etc of this world were all private individuals sponsoring and building amazing instruments for space exploration, it’s really just a natural progression on from this. We’re partnering closely with the Planetary Society on this, as they have common goals and interests to us, and also with National Geographic. We feel this really does open up space to a whole new group of people, and it’s apparent from the phenomenal interest we’ve had from Kickstarter, and the thousands of people who’ve pledged their support, that this vision was right.
NH – Planetary Resources has some huge goals in terms of asteroids in future, but you seem to have a very balanced and phased scientific plan to study and then proceed to the larger scale operations. Does this come from your science background?
CL – As I said, I grew up in dairy country in Wisconsin, where I had to really make my own opportunities be a part of this industry, there was no space there. On saying that, I have been an advocate of space pretty much all my life, and yes, I guess my scientific background, and experience with working at JPL has come to bear in Planetary Resources. We have a solid plan in terms of risk management with our “swarm” mentality, of sending up lots of spacecraft, and even if one or more fails, we’ll still be able to get valuable science data. I see it really in that lots of people have big ideas, and set up companies with them, but then after initial investment dries up, the ideas may still be big and there, but there is no way to pursue them.
We’ve all come from companies which have seen this kind of mindset in the past, and now, whilst we love employing students and college graduates who have big ideas, who take chances, we have a plan, a long term, and sustainable plan, and yes, we’re taking a steady approach to this, so that we can guarantee that our investors get a return on what they have supported.
NH – Can you give us a timeline for what Planetary Resources aim to achieve?
CL – Our first test launch will be as early as 2014, and then in 2015 we’ll start with the space telescopes using the Arkyd technology. By 2017 we hope to be identifying and on our way to classification of potentially interesting NEO targets for future mining. By the early 2020’s the aim is to be doing extraction from asteroids, and starting sample return missions.
NH – You were and still it seems from all I have read, remain passionate about student involvement, with SEDS etc, what could you say to younger people inspired by what you’re doing to encourage them to get in to the space industry?
CL – Tough one, but I’d say that looking at the people you admire, always remember that they are not superhuman, they are like you and me, but to have goals, take chances and be determined is a great way to look forward. The SEDS movement played a big part in my early life, and I would encourage any student to get involved in that for sure.
NH – In conclusion, what would be your ultimate goal as a pioneer of the new frontier in space exploration?
CL – Our ultimate goal is to be the developer of the economic engine that makes space exploration commercially viable. Once we have established that, we can then look at more detailed exploration of space, with tourism, scientific missions, and extending our reach out even further. I’ve already been a part of placing three missions on the surface of Mars, so nothing really is beyond our reach.
Nick’s closing comments :
I first met Chris at the Spacefest V conference in Tucson, where he gave me a preview of the Arkyd space telescope. There is no doubt in my mind that after meeting him, that he and the team at Planetary Resources will succeed in their mission. A quite brilliant individual, but humble with it, someone who you can spend hours talking to and come away feeling truly inspired. This interview we talked for what seemed like hours, and Chris said I could have written a book with the answers he gave, I hope this article gives you some taste however of the person behind the missions which, at the new frontier of exploration, much like the prospectors in the Gold Rush, are charting new and unknown, yet hugely exiting territories. As the old saying goes…and possibly more aptly then ever… watch this space.
Map showing all galaxies in the local universe color-coded by their distance to us: blue galaxies are the closest, and red are farther, up to 300 million light-years away. Credit: University of Hawaii.
Researchers with the Cosmic Flows project have been working to map both visible and dark matter densities around our Milky Way galaxy up to a distance of 300 million light-years, and they’ve now released this new video map which shows the motions of structures of the nearby Universe in greater detail than ever before.
“The complexity of what we are seeing is almost overwhelming,” says researcher Hélène Courtois, associate professor at the University of Lyon, France, and associate researcher at the Institute for Astronomy (IfA), University of Hawaii (UH) at Manoa. Courtois narrates the video.
The video zooms into our local area of the Universe — our Milky Way galaxy lies in a supercluster of 100,000 galaxies — and then slowly draws back to show the cosmography of the Universe out to 300 million light years.
The map shows how the large-scale structure of the Universe is a complex web of clusters, filaments, and voids. Large voids are bounded by filaments that form superclusters of galaxies. These are the largest structures in the universe.
The team explains:
The movements of the galaxies reveal information about the main constituents of the Universe: dark energy and dark matter. Dark matter is unseen matter whose presence can be deduced only by its effect on the motions of galaxies and stars because it does not give off or reflect light. Dark energy is the mysterious force that is causing the expansion of the universe to accelerate.
This is an image of a unique eclipse as viewed by NASA's Solar Dynamics Observatory, with a model of the moon from NASA's Lunar Reconnaissance Orbiter replacing the lunar shadow. Credit: NASA/SDO/LRO/GSFC
You’ve probably never before seen an image like the one above. That’s because it is the first time something like this has ever been created, and it is only possible thanks to two fairly recent NASA missions, the Solar Dynamics Observatory and the Lunar Reconnaissance Orbiter. We’ve shared previously how two or three times a year, SDO goes through “eclipse season” where it observes the Moon traveling across the Sun, blocking its view.
Now, Scott Wiessinger and Ernie Wright from Goddard Space Flight Center’s Scientific Visualization Studio used SDO and LRO data to create a model of the Moon that exactly matches SDO’s perspective of a lunar transit from October 7, 2010. They had to precisely match up data from the correct time and viewpoint for the two separate spacecraft, and the end result is this breathtaking image of the Sun and the Moon.
“The results look pretty neat,” Wiessinger said via email, “and it’s a great example of everything working: SDO image header data, which contains the spacecraft’s position; our information about lunar libration, elevation maps of the lunar surface, etc. It all lines up very nicely.”
‘Nicely’ is an understatement. How about “freaking awesome!”
And of course, they didn’t just stop there.
his is an up close shot of two NASA images: An image rendered from a model of the moon from the Lunar Reconnaissance Orbiter overlaid onto an image of the sun from the Solar Dynamics Observatory, during a lunar transit as seen by SDO on Oct. 7, 2010. The various features of the moon’s horizon are labeled. Credit: NASA/SDO/LRO/GSFC
Since the data from both spacecraft are at such high resolution, if you zoom in to the LRO image, features of the Moon’s topography are visible, such as mountains and craters. This annotated image shows what all is visible on the Moon. And then there’s the wonderful and completely unique view in the background of SDO’s data of the Sun.
So while the imagery is awesome, this exercise also means that both missions are able to accurately provide images of what’s happening at any given moment in time.
The image on the left is a view of the sun captured by NASA’s Solar Dynamics Observatory on Oct. 7, 2010, while partially obscured by the moon. Looking closely at the crisp horizon of the moon against the sun shows the outline of lunar mountains. A model of the moon from NASA’s Lunar Reconnaissance Orbiter has been inserted into a picture on the right, showing how perfectly the moon’s true topography fits into the shadow observed by SDO. Credit: NASA/SDO/LRO/GSFC
The CRaTER instrument aboard NASA's Lunar Reconnaissance Orbiter measures the effect of cosmic rays on "human tissue-equivalent" plastic. (NASA)
It could work, say researchers from the University of New Hampshire and the Southwest Research Institute.
One of the inherent dangers of space travel and long-term exploration missions beyond Earth is the constant barrage of radiation, both from our own Sun and in the form of high-energy particles originating from outside the Solar System called cosmic rays. Extended exposure can result in cellular damage and increased risks of cancer at the very least, and in large doses could even result in death. If we want human astronauts to set up permanent outposts on the Moon, explore the dunes and canyons of Mars, or mine asteroids for their valuable resources, we will first need to develop adequate (and reasonably economical) protection from dangerous space radiation… or else such endeavors will be nothing more than glorified suicide missions.
While layers of rock, soil, or water could protect against cosmic rays, we haven’t yet developed the technology to hollow out asteroids for spaceships or build stone spacesuits (and sending large amounts of such heavy materials into space isn’t yet cost-effective.) Luckily, there may be a much easier way to protect astronauts from cosmic rays — using lightweight plastics.
While aluminum has always been the primary material in spacecraft construction, it provides relatively little protection against high-energy cosmic rays and can add so much mass to spacecraft that they become cost-prohibitive to launch.
Using observations made by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) orbiting the Moon aboard LRO, researchers from UNH and SwRI have found that plastics, adequately designed, can provide better protection than aluminum or other heavier materials.
“This is the first study using observations from space to confirm what has been thought for some time—that plastics and other lightweight materials are pound-for-pound more effective for shielding against cosmic radiation than aluminum,” said Cary Zeitlin of the SwRI Earth, Oceans, and Space Department at UNH. “Shielding can’t entirely solve the radiation exposure problem in deep space, but there are clear differences in effectiveness of different materials.”
Zeitlin is lead author of a paper published online in the American Geophysical Union journal Space Weather.
A block of tissue-equivalent plastic (TEP) Credit: UNH
The plastic-aluminum comparison was made in earlier ground-based tests using beams of heavy particles to simulate cosmic rays. “The shielding effectiveness of the plastic in space is very much in line with what we discovered from the beam experiments, so we’ve gained a lot of confidence in the conclusions we drew from that work,” says Zeitlin. “Anything with high hydrogen content, including water, would work well.”
The space-based results were a product of CRaTER’s ability to accurately gauge the radiation dose of cosmic rays after passing through a material known as “tissue-equivalent plastic,” which simulates human muscle tissue.
(It may not look like human tissue, but it collects energy from cosmic particles in much the same way.)
Prior to CRaTER and recent measurements by the Radiation Assessment Detector (RAD) on the Mars rover Curiosity, the effects of thick shielding on cosmic rays had only been simulated in computer models and in particle accelerators, with little observational data from deep space.
The CRaTER observations have validated the models and the ground-based measurements, meaning that lightweight shielding materials could safely be used for long missions — provided their structural properties can be made adequate to withstand the rigors of spaceflight.
In reviewing the book “Beyond the Solar System: Exploring Galaxies, Black Holes, Alien Planets, and More; A History with 21 Activities” by Mary Kay Carson, UT writer Eva Gallant described it as “written for children and for the inquisitive child within us.”
Thanks to the publisher, Universe Today has three free copies of this book to giveaway — perfect for the kids in your life (even if that’s you!)
This contest will run for a week starting today, so get your entries in! How?
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, June 19, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
We’re only going to use these email addresses for Universe Today giveaways/contests and announcements. We won’t be using them for any other purpose, and we definitely won’t be selling the addresses to anyone else. Once you’re on the giveaway notification list, you’ll be able to unsubscribe any time you like.
It is probably a safe bet that even as children, Universe Today readers gazed at the night sky with awe and wonder. Did you wish upon the first star light, star bright in the sky? Cultures across time have spun tales around constellations – images projected on the night’s expanse based on our perceptions. As science and technology progressed we realized the vast depths of space are truly full of wonder. There’s an incredible array of amazing things to be discovered, researched and understood.
The images within the chapters are well appointed. For example, at the beginning of the book during a journey from prehistory-1600 you’ll find a fantastic Library of Congress image of the Great Bear constellation, joined by the British Library’s ancient Chinese Star Map, that dates back to the 600’s A.D. This reviewer will definitely be trying some of the activities explained among the chapters such as “Make a 3-D Starscape” found on page 32. This craft project demonstrates the artificial grouping we’ve given our constellations and shows that they are actually comprised of stars great distances from each other and us.
Perhaps the best review of this book comes from my 8 year old daughter. For the past week, she has been reading this book in the car while travelling to school. A recent morning’s question from the back seat was “What’s a pulsar?” She’s excited to try all of the activities; first up will be making a radio picture found on page 82 or turning a friend into a pulsar by spinning them in a chair with two flashlights on page 89. In addition to her “two thumbs” up eagerness to read this every morning, she simply stated “I love this book.”
I extend a thank you to the author for creating a fun, educational STEM source that attracted not only the attention of my science oriented 14 year old boy, but also my daughter, who is as equally bright, capable and curious about the world around her.
OK, it’s a bad gag, I know. But the movie Man of Steel isn’t the only thing that’s “super” about June this year. The closest full Moon of 2013 occurs on June 23, when it will be 356,991 kilometres from Earth, within 600 kilometres of its closest possible approach. When the Moon is closest to Earth in its orbit, it also appears just a bit larger in the sky. But that’s if you’re really paying attention, however!
Some claims circulating on the Internet tend to exaggerate how large the Moon will actually appear. And as for the assertions that the Moon will look bright purple or blue on June 23, that’s just not true. As seems to happen every year, the term “supermoon” has once again reared its (ugly?) head across ye ole Internet. Hey, it’s a teachable moment, a good time to look at where the term came from, and examine the wonderful and wacky motion of our Moon.
I’ll let you in on a small secret. Most astronomers, both of the professional and backyard variety, dislike the informal term “supermoon”. It arose in astrology circles over the past few decades, and like the term “Blue Moon” seems to have found new life on the Internet. A better term from the annuals of astronomy for the near-coincidence of the closest approach of the Full Moon would be Perigee Full Moon. And if you really want to be archaic, Proxigean Moon is also acceptable.
On June 23, 2013, the Moon will be full at 7:32 AM EDT/ 11:32 UT, only 20 minutes after it reaches perigee, or its closest point to Earth in its orbit.
You can see the change in apparent size of the Moon (along with a rocking motion of the Moon known as nutation and libration) in this video from the Goddard Space Flight Center’s Scientific Visualization Studio. You can also see full animations for Moon phases and libration for 2013 from the northern hemisphere and southern hemisphere.
And all perigees are not created equal, either. Remember, a Full Moon is an instant in time when the Moon’s longitude along the ecliptic is equal to 180 degrees. Thus, the Full Moon rises (unless you’re reading this from high polar latitudes!) opposite as the Sun sets. Perigee also oscillates over a value of just over 2 Earth radii (14,000 km) from 356,400 to 370,400 km. And while that seems like a lot, remember that the average distance to the Moon is about 60 earth radii, or 385,000 km distant.
Astronomers yearn for kryptonite for the supermoon. The Moon passes nearly as close every 27.55 days, which is the time that it takes to go from one perigee to another, known as an anomalistic month. This is not quite two days shorter than the more familiar synodic month of 29.53 days, the amount of time it takes the Moon to return to similar phase (i.e. New to New, Full to Full, etc).
This offset may not sound like much, but 2 days can add up. Thus, in six months time, we’ll have perigee near New phase and the smallest apogee Full Moon of the year, falling in 2013 on December 19th. Think of the synodic and anomalistic periods like a set of interlocking waves, cycling and syncing every 6-7 months.
You can even see this effect looking a table of supermoons for the next decade;
Super Moons for the Remainder of the Decade 2013-2020.
Year
Date
Perigee Time
Perigee Distance
Time from Full
Notes
2013
June 23
11:11UT
356,989km
< 1 hour
2013
July 21
20:28UT
358,401km
-21 hours
2014
July 13
8:28UT
358,285km
+21 hours
2014
August 10
17:44UT
356,896km
< 1 hour
2014
September 8
3:30UT
358,387km
-22 hours
2015
August 30
15:25UT
358,288km
+20 hours
2015
September 28
1:47UT
356,876km
-1 hour
Eclipse
2015
October 26
13:00UT
358,463km
-23 hours
2016
October 16
23:37UT
357,859km
+19 hours
Farthest
2016
November 14
11:24UT
356,511km
-2 hours
Closest
2017
December 4
8:43UT
357,495km
+16 hours
2018
January 1
21:56UT
356,565km
-4 hours
2019
January 21
19:59UT
357,344km
+14 hours
Eclipse
2019
February 19
9:07UT
356,761km
-6 hours
2020
March 10
6:34UT
357,122km
+12 hours
2020
April 7
18:10UT
356,908km
-8 hours
Sources: The fourmilab Lunar Perigee & Apogee Calculator & NASA’s Eclipse Website 2011-2020.Note: For the sake of this discussion, a supermoon is defined here as a Full Moon occurring within 24 hours of perigee. Other (often arbitrary) definitions exist!
Note that the supermoon slowly slides through our modern Gregorian calendar by roughly a month a year.
In fact, the line of apsides (an imaginary line drawn bisecting the Moon’s orbit from perigee to apogee) completes one revolution every 8.85 years. Thus, in 2022, the supermoon will once again occur in the June-July timeframe.
To understand why this is, we have to look at another unique feature of the Moon’s orbit. Unlike most satellites, the Moon’s orbit isn’t fixed in relation to its primaries’ (in this case the Earth’s) equator. Earth rotational pole is tilted 23.4 degrees in relation to the plane of its orbit (known as the ecliptic), and the Moon’s orbit is set at an inclination of 5.1 degrees relative to the ecliptic. In this sense, the Earth-Moon system behaves like a binary planet, revolving around a fixed barycenter.
The two points where the Moon’s path intersects the ecliptic are known as the ascending and descending nodes. These move around the ecliptic as well, lining up (known as a syzygy) during two seasons a year to cause lunar and solar eclipses.
The complex motion of the Moon, depicting the movement of the nodes versus the average movement of the line of apsides. (Credit: Geologician, Homunculus 2. Wikimedia Commons graphic under a Creative Common Attribution 3.0 Unported license).
But our friend the line of apsides is being dragged backwards relative to the motion of the nodes, largely by the influence of our Sun. Not only does this cause the supermoons to shift through the calendar, but the Moon can also ride ‘high’ with a declination of around +/-28 degrees relative to the celestial equator once every 19 years, as happened in 2006 and will occur again in 2025.
Falling only two days after the solstice, this month’s supermoon is also near where the Sun will be in December and thus will also be the most southerly Full Moon of 2013. Visually, the Full Moon only varies 14% in apparent diameter from 34.1’ (perigee) to 29.3’ (apogee).
Can you see the difference? A side by side comparison of the perigee and apogee Moon. (Credit: Inconstant Moon).
A fun experiment is to photograph the perigee Moon this month and then take an image with the same setup six months later when the Full Moon is near apogee. Another feat of visual athletics would be to attempt to visually judge the Full Moons throughout a given year. Which one do you think is largest & smallest? Can you discern the difference with the naked eye? Of course, you’d also have to somehow manage to insulate yourself from all the supermoon hype!
A comparison of the rising Moon (left) & the Full Moon high in the sky… as you can see, atmospheric refraction actually tends to “shrink” the apparent size of a rising Moon! (Credit & Copyright: Richard Fleet (@dewbow) The Moon Illusion).
Many folks also fall prey to the rising “Moon Illusion.” The Moon isn’t visually any bigger on the horizon than overhead. In fact, you’re about one Earth radii closer to the Moon when it’s at the zenith than on the horizon. This phenomenon is a psychological variant of the Ponzo illusion.
The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Note the size difference. Image Credit: Marco Langbroek, the Netherlands, via Wikimedia Commons.
Here are some of the things that even a supermoon can’t do, but we’ve actually heard claims for:
– Be physically larger. You’re just seeing the regular-sized Moon, a tiny bit closer.
– Cause Earthquakes. Yes, we can expect higher-than-normal Proxigean ocean tides, and there are measurable land tides that are influenced by the Moon, but no discernible link between the Moon and earthquakes exists. And yes, we know of the 2003 Taiwanese study that suggested a weak statistical correlation. And predicting an Earthquake after it has occurred, (as happened after the 2011 New Zealand quake) isn’t really forecasting, but a skeptical fallacy known as retrofitting.
– Influence human behavior. Well, maybe the 2013 Full Moon will make some deep sky imagers pack it in on Sunday night. Lunar lore is full of such anecdotes as more babies are born on Full Moon nights, crime increases, etc. This is an example the gambler’s fallacy, a matter of counting the hits but not the misses. There’s even an old wives tale that pregnancy can be induced by sleeping in the light of a Full Moon. Yes, we too can think of more likely explanations…
– Spark a zombie apocalypse. Any would-be zombies sighted (Rob Zombie included) during the supermoon are merely coincidental.
Do get out and enjoy the extra illumination provided by this and any other Full Moon, super or otherwise. Also, be thankful that we’ve got a large nearby satellite to give our species a great lesson in celestial mechanics 101!
A 360° horizon panorama taken from southern Alberta on June 5, 2013, showing the Milky Way, a low aurora to the north, perpetual twilight glow to the north (left of centre) and bands of green airglow across the sky, and the ATV-4 Albert Einstein heading to the International Space Station. Credit and copyright: Alan Dyer.
Yep, you really want to click on this image to see the larger version on Flickr. Wow — what a view!!
This is a 360° horizon pan, seen by Alan Dyer — who has an aptly named website, The Amazing Sky. This is a view seen from southern Alberta on June 5, 2013, and there is a lot going on in this image. Alan described it on Flickr: “There’s the Milky Way arching across the sky on the right, a low aurora to the north, perpetual twilight glow to the north (left of center) and bands of green airglow across the sky. Left of the house and also left of the main area of Milky Way are horizon glows from urban light pollution. A satellite, the ESA Einstein ATV going to the ISS, is at left of frame.”
I get extremely excited if I can see *one* of those things in a night, and here Alan has captured all at once — superb!
But wait, there’s more!
On June 10, Alan was able to take a timelapse of the Northern Lights and some noctilucent clouds, and it is gorgeous. See below:
Alan said on his website, “This was certainly one of the best NLC displays I’d seen and my best shot at capturing them.”
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Thirty-six of the stars in this open star cluster, NGC 3766, are a variable star never seen before. Observations were made with the European Southern Observatory's La Silla Observatory. Credit: ESO
A new kind of variable star — 36 of that type, in fact — has been found in a single star cluster. Astronomers don’t even have a name for the star type yet, but feel free to leave some suggestions in the comments!
For now, however, astronomers are wondering what the implications are for our understanding of the stellar interiors.
“The very existence of this new class of variable stars is a challenge to astrophysicists,” stated Sophie Saesen, an astronomer at Geneva Observatory who participated in the research.
“Current theoretical models predict that their light is not supposed to vary periodically at all, so our current efforts are focused on finding out more about the behaviour of this strange new type of star.”
The head-scratching began when astronomers used a European Southern Observatory telescope to gaze at the “Pearl Cluster” (NGC 3766), an open star cluster about 5,800 light years from Earth.
Over seven years of observations with the Leonhard Euler Telescope (taking periodic measurements of brightness), astronomers spotted 36 stars with variable periods of between 2 and 20 hours.
The four-foot (1.2-meter) Leonhard Euler Telescope at the European Southern Observatory. Credit: M. Tewes/ESO
Variable stars have been known for centuries, and many of them are tracked by amateur organizations such as the American Association of Variable Observers. As best as astronomers can figure, the stars become brighter and dimmer due to changes on the inside — stellar vibrations or “quakes” studied under a field called asteroseismology.
A special type of variable stars, called Cepheid variables, can provide accurate measurements of distance since they have an established ratio between luminosity and the period of their variability.
Studying various types of variable stars has provided some insights.
“Asteroseismology of ß Cep[hei] stars, for example, has opened the doors in the past decade to study their interior rotation and convective core,” the astronomers stated in a paper on the research.
The variations in brightness can be interpreted as vibrations, or oscillations within the stars, using a technique called asteroseismology. The oscillations reveal information about the internal structure of the stars, in much the same way that seismologists use earthquakes to probe the Earth’s interior. Credit: Kepler Astroseismology team.
Despite the well-known nature of variable stars, few of them have been studied in open clusters such as NGC 3766.
The reason is it takes a lot of telescope time to take a look at the star — sometimes, years. And time with telescopes is both expensive and precious, making it difficult to allocate the time required.
“Stellar clusters are ideal environments to study stellar variability because some basic properties and the evolutionary status of individual star members can be derived from the properties of the cluster,” the astronomers stated.
“It, however, requires extensive monitoring on an as-long-as-possible time base line. This requirement may explain why not many clusters have been studied for their variability content so far, compared to the number of known and characterized clusters.”
These particular stars in NGC 3766, however, were puzzling.
“The stars are somewhat hotter and brighter than the Sun, but otherwise apparently unremarkable,” ESO stated, yet they had variations of about 0.1% of each star’s normal brightness.
Cepheid Variable Star. Credit: Hubble Space Telescope
It’s possible, but not proven yet, that perhaps the stars’ spin has something to do with the brightness.
Some of the observed objects whip around at speeds so fast that some material might be punted away from the star and into space, the astronomers wrote in a press release.
“In those conditions, the fast spin will have an important impact on their internal properties, but we are not able yet to adequately model their light variations,” stated Nami Mowlavi, another Geneva Observatory astronomer who led the paper.
Also, astronomers haven’t named this class of stars yet. Do you have any ideas? For more information and to generate suggestions, you can read the paper here in Astronomy & Astrophysics. Then you can leave your thoughts in the comments.
