The Pacific Ring of Fire, a strong of volcanic . Credit:
The Pacific Ring of Fire wraps around the Pacific Ocean, including countries like Japan, Canada, New Zealand and Chile. And the inhabitants within those countries are prone to… oh… killer earthquakes, volcanoes and tsunamis. Let’s chat about the history of this region and the kinds of risks they face.
And the podcast is also available as a video, as Fraser and Pamela now record Astronomy Cast as part of a Google+ Hangout (usually recorded every Monday at 3 pm Eastern Time):
This composite Hubble Space Telescope picture shows the location of a newly discovered moon, designated S/2004 N 1, orbiting the giant planet Neptune, nearly 4.8 billion km (3 billion miles) from Earth. Credit: NASA, ESA, and M. Showalter (SETI Institute).
It took sharp and patient eyes, but researcher Mark Showalter of the SETI Institute has found a tiny moon orbiting Neptune that’s never been seen before. Showalter used archival data from the Hubble Space Telescope to find the moon, designated S/2004 N 1, which is estimated to be no more than 19 km (12 miles) across, making it the smallest known moon in the Neptunian system. This is the 14th known moon of Neptune.
S/2004 N 1 is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye, NASA said. Even Voyager 2 –which flew past Neptune in 1989 to survey planet’s system of moons and rings – didn’t catch a view of this moon, even though data from Voyager 2 revealed several other moons.
Neptune photographed by Voyager 2. Image credit: NASA/JPL
Showalter was studying the faint arcs, or segments of rings, around Neptune earlier this month.
“The moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system,” he said. “It’s the same reason a sports photographer tracks a running athlete — the athlete stays in focus, but the background blurs.”
The method involved tracking the movement of a white dot that appears over and over again in more than 150 archival Neptune photographs taken by Hubble from 2004 to 2009.
Showalter noticed the white dot about 100,000 km (65,400 miles) from Neptune, located between the orbits of the Neptunian moons Larissa and Proteus. Showalter plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours.
Showalter should get the “Eagle Eyes” award for 2013!
It’s a moment that you’ve always dreaded – you stepped away from your hiking buddies to take a photo, but on the way back you slipped down an embankment. Now you’re isolated, you can’t find the trail or your friends, and you’re in unfamiliar woods. You try your phone – no signal. How did people navigate before GPS, anyway? In The Lost Art of Finding Our Way, author John Edward Huth aims to show us just that. In a richly-illustrated 544 pages, Huth tries to illuminate the techniques that let man circumnavigate the globe, long before the first GPS satellite was launched.
The book is divided into roughly two halves, with the first being historical tales and discussions of techniques used by ancient navigators to find their way. The Norse are here, as are Pacific Islanders and European sailors: all have lessons to teach us about our environment, from the way that waves form around a cluster of islands, to how to use a cross-staff to estimate the position of a star on a heaving ship deck. Following this, the second half of the book is more abstract, dealing with factors useful to navigators: like weather prediction, or the factors that create the swell and tides in the ocean.
I found the first half of the book to be the most interesting, as the practical techniques for, say, triangulating your position with only a map and a compass are very interesting to a city-bound boy. The second half was much tougher reading as it is quite dry, often reading like a physics textbook. Descriptions are clear, although I will note that if you were looking for a practical manual to teach you navigation, this book isn’t it. It will, for instance, explain how dip angle and refraction in the atmosphere complicate accurate estimates of the horizon and the elevation of stars—but stop short of pointing you a resource to help correct for these inaccuracies.
It’s perhaps ironic that The Lost Art of Finding Our Way sometimes feels a little directionless. Maybe it’s because the very scope of the book is so large: in the one book, you can find a discussion of how search parties can be most efficient; descriptions of the magnetic field variations across the Earth’s surface, and their causes; speculation as to why many cultures have ‘great flood’ myths; and an explanation of the physics of wind interacting with sails.
Overall, this book is an impressive attempt to give a broad overview of a number of navigation techniques. Unfortunately it is marred by its own ambition, and the result is a book that can at times feel random, aimless and meandering.
Seriously, for all you coffee addicts, this is science. You may recall how astronaut Don Pettit (known as Mr. Fixit in space) invented a Zero-G coffee cup. But there’s an experiment on board the International Space Station called the Capillary Flow Experiment that is delving even further into how liquids behave in space.
Coffee is not the only liquid that behaves quite differently in space as opposed to on Earth. There are things like cryogenic fuels, thermal coolants, water and urine, too. As NASA says, “The behavior of fluids is one of the most un-intuitive things in all of space flight.”
This poses a challenge for engineers designing spacecraft systems that use fluids. “Our intuition is all wrong,” said physics professor Mark Weislogel of Portland State University, who working with the Capillary Flow Experiment. “When it comes to guessing what fluids will do in new systems, we are often in the dark.”
Weislogel and his colleagues are now looking at interior corners on containers and how that affects liquid flow. Just like on Pettit’s Zero-G coffe cup (see video below), if two solid surfaces meet at a narrow-enough angle, fluids in microgravity naturally flow along the joint —no pumping required.
NASA says this capillary effect could be used to guide all kinds of fluids through spacecraft, from cryogenic fuel to recycled waste water. The phenomenon is difficult to study on Earth, where it is damped by gravity, but on the space station large scale corner flows are easy to create and observe.
Who says coffee isn’t like your morning rocket fuel!
Have you ever noticed that the Moon always looks the same? Sure, the phase changes, but the actual features on the Moon always look the same from month to month.
Does the Moon rotate? What’s going on?
From our perspective here on Earth, the Moon always shows us the same face because it’s tidally locked to our planet. At some point in the distant past, the Moon did rotate from our perspective, but the Earth’s gravity kept pulling unevenly at the Moon, slowing its rotation. Eventually the Moon locked into place, always displaying the same side to us.
But if you looked down on the Earth-Moon system from the north celestial pole, from the perspective of Polaris, the North Star, you’d see that the Moon actually does rotate on its axis. In fact, as the Moon travels around the Earth in a counter-clockwise orbit every 27.5 days, it also completes one full rotation on its axis – also moving in a counter-clockwise direction.
If you look at a time lapse animation of the Moon moving entirely through its phases over the course of a month, you’ll notice a strange wobble, as if the Moon is rocking back and forth on its axis a bit.
This is known as libration.
On average, the Moon is tidally locked to the Earth’s surface. But its actual orbit is elliptical, it moves closer and then more distant from the Earth.
When the Moon is at its closest point, it’s rotation is slower than its orbital speed, so we see an additional 8 degrees on its eastern side. And then when the Moon is at the most distant point, the rotation is faster than its orbital speed, so we can see 8 degrees on the Western side.
Libration allowed astronomers to map out more of the Moon’s surface than we could if the Moon followed a circular orbit.
Until the space age, half the Moon was hidden from us, always facing away. This hemisphere of the Moon was finally first observed by the Soviet Luna 3 probe in 1959, followed by the first human eyes with Apollo 8 in 1968.
The two hemispheres of the Moon are very different.
While the near side is covered with large basaltic plains called maria, the far side is almost completely covered in craters. The reasons for this difference is still a mystery to planetary scientists, but it’s possible that a second Moon crashed into it, billions of years ago, creating the strange surface we see today.
So yes, the Moon does rotate.
But its rotation exactly matches its orbit around the Earth, which is why it looks like it never does.
The UNESCO World Heritage Site of Persopolis, Iran (image credit: Oshin D. Zakarian/TWAN).
Citizen scientists have discovered planets beyond our Solar System and established morphological classifications for thousands of galaxies (e.g., the Planet Hunters and Galaxy Zoo projects). At an upcoming meeting of planetary scientists, Hamed Pourkhorsandi from the University of Tehran will present his efforts to mobilize citizens to identify impact craters throughout Persia. Pourkhorsandi said he is recruiting volunteers to identify craters using Google Earth, while continuing to seek sightings of fireballs cited in ancient books and among rural folk. Discovering impact craters is an important endeavour, since it helps astronomers estimate how many asteroids of a particular size strike Earth over a given time (i.e., the impact frequency). Indeed, that is especially relevant in light of the recent meteor explosion over Russia this past February (see the UT article here), which hints at the potentially destructive nature of such occurrences.
Satellite images have facilitated the detection of impact sites such as the Kamil and Puka craters, which were identified by V. de Michele and D. Hamacher using Google Earth, respectively (see the UT article here). Pourkhorsandi noted that, “Free access to satellite images has led to the investigation of earth’s surface by specialists and nonspecialists, attempts that have led to the discovery of new impact craters around the globe. [Yet] few researches on this topic have been done in the Middle East.” Incidentally, citizens are likewise being recruited to classify craters and features on other bodies in the Solar System (e.g., the Moon Zoo project).
The Kamil impact crater in Egypt was discovered by V. de Michele using Google Earth, and H. Pourkhorsandi is recruiting volunteers to discover such structures throughout Persia following a similar approach (image credit: L. Folco).
In his paper, Pourkhorsandi describes examples of two targets investigated thus far: “1. a circular structure with a diameter of 200 m (33°21’57”N 58°14’24”E). [However,] there is no sign of … meteoritic fragments in the region that are primary diagnostic indicators for small size impact craters.” The second target is tied to an old tale, and note that the Puka crater in Australia was identified by following-up on an old Aboriginal story. However, Pourkhorsandi states that a field study of the second target (28°24’52” N 60°34’44” E) revealed that the crater is not associated with an impactor from space.
“Beside these structures, field studies on other craters in Persia are in progress, the outcomes of which will be announced in the near future,” said Pourkhorsandi.
Pourkhorsandi underscores that numerous meteorites have been found in desert regions throughout the world, yet scant attention has been given to Persian deserts (e.g., the Lut desert). The Lut desert in Persia extends over several thousand square kilometres and is one of the hottest places on Earth (featuring land surface temperatures upwards of 70 degrees Celsius). Pourkhorsandi noted that in 2005 a ‘curious stone’ was recovered in the Lut desert and subsequent work revealed its extraterrestrial origin.
He went on to remark that, “Three recent short field trips to the central Lut desert led to the collection of several meteoritic fragments, which points to large concentrations of meteoritic materials in the area.” Some of those fragments are shown in the figure below, and the broader region is likely a pertinent place for citizen scientists to continue the hunt for impact craters in Persia.
Pourkhorsandi concluded by telling the Universe Today, “In the future we aim to expand our efforts with the help of additional people, and will direct individuals to scan other regions of the planet. Simultaneously, we have commenced a comprehensive analysis of meteorites in the Lut desert with fellow European scientists.”
H chondrite fragments found in the Lut desert (in Persia) are argued to be extraterrestrial in origin (image credit: Fig. 3 in Pourkhorsandi 2013/LPI).
Canadian astronaut Jeremy Hansen during 2010 geology training near Gila Bend, Arizona. Credit: Canadian Space Agency
This week, Canadian astronaut Jeremy Hansen is on his way to a remote island in the Canadian Arctic. We realize this sounds like the opening episode for Survivor, but his purpose up there is more scientific: to conduct field geology.
Geology work, and training for sample collection is not as easy as simply picking up whatever you see on the ground. It’s important to get a range of rocks that represent the geology of the area. You also need to photograph and otherwise document the area in such a way that geologists can learn more about how it was formed, among other duties.
A trained observer can come to preliminary conclusions while wandering around in the field, and possibly change his or her sample-gathering strategy in accordance with that. The Apollo moon missions were replete with examples of this, with one of the more famous ones perhaps being when Harrison Schmitt (who, unlike his colleagues, had a Ph.D. in geology) stumbled across some orange soil during Apollo 17. This was probably evidence of an ancient fire-fountain of lava on the moon.
But Schmitt certainly wasn’t expecting to see that when he walked on the surface. Check out his reaction around 1:50 in this video:
Hansen will join a Western University group to study “impact cratering processes while learning methods and techniques for conducting geological fieldwork that can be applied to sites beyond our planet,” stated the Canadian Space Agency. To make it feel more space mission-like, the group will be working with limited supplies and support.
Geology training isn’t important just on the ground, but also in observing from space. As Hansen points out on this video, from time to time astronauts on the International Space Station are called upon to observe features from their orbital perches. If they understand the processes behind what they see, their descriptions, videos and photos will be more scientific.
Hansen will stay on Devon Island until about July 25, studying impact crater processes along with the rest of the team. Updates should be available on his Twitter feed as well as through the Canadian Space Agency.
And by the way, Canada was also useful to astronauts during the Apollo years. One famous geology site was at Sudbury, Ont. This website highlights the activities of the Apollo 16 crew, which was looking at craters in the area.
Screenshot from the video showing where Hebes Chasma is located on Mars. Via ESA.
Take a ride through a Hebes Chasma, a canyon just north of the largest canyon on Mars – and the Solar System — Valles Marineris. The video provides an awesome view, but this is not a wild ride with Luke Skywalker through trenches of the Death Star …. it’s more like a tourist pleasure cruise which provides picturesque views of this 8 km-deep canyon.
ESA provides all the tourist info of what you are seeing:
The movie glides over impact craters pockmarking the plains separating the troughs, down cliff faces scarred by landslides, and along the rough valley floor.
In some parts of the valley Mars Express has detected water-bearing minerals, suggesting that significant quantities of water may have once flowed here.
The formation of Hebes Chasma is likely connected to the nearby volcanic Tharsis region, home to the planet’s vast Olympus Mons volcano.
During periods of intense volcanism the whole region stretched upwards, causing tremendous stress in the crust further way. Unable to withstand the strain, the crust ripped open, collapsing into the chasms found in and around Valles Marineris.
We’re going to try a new experiment with the Virtual Star Party this week. I’m going to post the video live on Universe Today as we start it up. Join us live here, or watch the archive after.
This week we had two active telescopes, from Cory Schmitz and Gary Gonnella. We did a quick tour through the nebula region of the Milky Way, making stops at the Ring Nebula, Dumbbell Nebula, Veil Nebula, Lagoon Nebula, Triffid Nebula, a couple of star clusters and even a galaxy.
If you want to join the Virtual Star Party live, we broadcast every Sunday night when it gets dark on the West Coast of North America. For July 21st, it’ll probably be 9:00 pm PDT/12:00 am EDT. But we’re much earlier in the Winter.
P.S. We’re always looking for new astronomers to join us. If you’ve got a telescope that can broadcast images to your computer, and you’d like to participate, please drop me an email at [email protected], and I’ll help you get set up.
Gennady Borisov, who lives in Naunchniy near the Crimean Observatory in the Ukraine, discovered the comet C/2013 N4 on July 8. He's shown here with his two telescopes. Credit: Oleg Bruzgalov
Ukrainian amateur astronomer Gennady Borisov discovered a brand new comet on July 8 near the bright star Capella in the constellation Auriga. The comet was confirmed and officially christened C/2013 N4 (Borisov) on July 13. At the time of discovery, Borisov was attending the Russian-Ukrainian “Southern Night” star party in Crimea, Ukraine. He nabbed the comet – his first – using an 8-inch (20-cm) f/1.5 wide field telescope of his own design equipped with a CCD camera.
Comet Borisov is the fuzzy spot with a brighter central region in this recent photo. Credit: Oleg Bruzgalov
The new comet is on the faint side, appearing as a small, fuzzy patch of 13th magnitude with a brighter center. To see it you’ll need at least a 10-inch (25-cm) telescope and the fortitude to rise in the wee hours before dawn. The reason for the early hour is Borisov’s location in Auriga, a constellation that doesn’t clear the horizon until shortly before the start of morning twilight. Faintness and low altitude will combine to make Comet Borisov an enticing if challenging object for amateur astronomers.
Animation of Comet Borisov compiled from multiple images. Credit: http://astronomamator.narod.ru/cometes/comet_anim.gif
C/2013 N4 is currently traveling through Auriga not far from the easy-to-spot naked eye star Beta and will slowly brighten as it approaches perihelion – closest point to the sun – on August 20 at a distance of 113.5 million miles (182.7 million km). Unfortunately its elongation or separation from the sun will be slowly shrinking in the coming weeks, causing the comet to drop lower in the sky as it approaches perihelion. Our fuzzy visitor misses Earth by a comfortable 192.5 million miles (310 million km) on August 11. It’s likely Comet Borisov won’t get much brighter than 12th magnitude. Astronomers are still working out the details of its orbit, so it’s possible brightness predictions could change in the near future.
C/2013 N4 (Borisov) tracks through northern Auriga not far from Capella in the coming nights. Positions are shown every 5 days at 3 a.m. CDT. The comet is faint and will require a more detailed chart and telescope to see. Created with Stellarium
Aside from how prominent or not Gennady’s comet will become, the most amazing thing is that he beat the automated surveys to the punch. These days nearly all comets and many asteroids are found by professional astronomers using robotic telescopes hooked up to sensitive cameras and computers. Large areas of the sky are covered each clear night. If a fuzzy, moving object is detected by the computer, astronomers are alerted, follow-up observations are made and the new object receives a letter, number and the survey’s name. That’s why there are a plethora of comets in the past 15 years with names like LINEAR(Lincoln Near-Earth Asteroid Survey), Pan-STARRS (Panoramic Survey Telescope & Rapid Response System), LONEOS (Lowell Observatory Near-Earth-Object Search) and others.
By dint of persistence, a smart plan and a keen eye, Gennady Borisov has made his mark in the sky. For that he deserves a well-deserved congratulations and round of applause!
Amateurs who wish to plot the comet on a star map using a star charting software program can get Comet Borisov’s orbital elements HERE. To follow the latest developments, check out Leonid Elenin’s blog. You might recall it was Elenin in 2010 who discovered famed comet C/2010 X1 (Elenin), blamed for everything from earthquakes to future world catastrophes. Instead, the comet proved so friable, it disintegrated as it approached the sun. Let’s see how Comet Borisov fares.
