The Earth Story

The previous launch attempt scrubbed after one of the 3 engines reported a thrust out of the range it was supposed to be in at the time of ignition - limits that may simply have been too conservative. SpaceX is currently planning to try one more time today, with a potential launch in about an hour.

Nebraska Sand Hills Extensive tracts of sand dunes are common throughout the central Great Plains and Rocky Mountains. The greatest among these is the Nebraska Sand Hills, which cover nearly 20,000 square miles (52,000km2) in north-central Nebraska and southernmost South Dakota.

FISHING FOR SOUTHERN LIGHTS During a fishing trip in the South of Tasmania – the southernmost State of Australia – Paul Anderson decided to take a walk down to the Tessellated Pavement (a natural formation of stone seen in the bottom of the image). The forecast for auroral activity was good, so he set up his camera after dinner and caught this amazing display. We covered the geology of tessellated pavement before at http://tinyurl.com/kgsmjj8 -CB courtesy of our sister page The Universe Paul is a writer for www.iheartthefly.com here's one of his articles on aurora in Iceland:http://iheartthefly.com/2013/11/20/fire-and-ice/ Image Credit and Copyright: Paul Anderson (taken May 18-19 2014) Canon 60D Lens Tokina 11-16mm Aperture f/2.8 Focal Length 11mm Exposure 20 seconds, white balance was set at 4200

The Sunspot Illusion

In the left image we see a small portion of the Sun in regular, white light. It reveals a surface covered in dark patches known as sunspots – or, in other words, the Sun’s version of acne. The number of sunspots visible on our Sun at any point in time is highly correlated with the star’s 11 year period of solar activity. In the years when the Sun is quieter, we do not see as many active features like sunspots and flares, and, consequently, get less impressive northern light displays. On the other hand, when the Sun is more lively and vivacious, we see more acne and radiation storms.

These blemishes are a sign of an active Sun. The image on the right shows the arcs and loops of magnetic field lines on the Sun as observed in extreme ultraviolet light. Sunspots appear where the lines are crowded together into active regions with a strong magnetic field. The pressure of this strong magnetic field can cause the temperature of the area to decrease and the light to fade, which is why the sunspots appear dark – relatively. A sunspot by itself, not near the rest of the Sun in a nighttime sky, would appear brighter than the Full Moon!

These sunspots are dim and cold when compared with the rest of the Sun, yes, but when you are using the brightest, most brilliant object in the Solar System as your base of comparison, everything else is inevitably going to fall a bit short. This is the same reason we do not label everyone smaller than Yao Ming as tiny. Comparing heights with one of the tallest men alive is an exercise in futility, even for a person taller than average.

While certainly chillier than the Sun’s average surface temperature of 5,500° Celsius, a sunspot is actually rather hot when compared to what we are used to here on Earth. They usually clock in with a temperature around 2700-3700° Celsius. The hottest, industrial furnaces at cremation centers turn bodies to ash at a little less than 1000° Celsius, so, when it comes to our tolerance levels and perspective, sunspots are beyond sweltering.

In this case, first impressions are deceiving, appearances are dependent on surroundings, and there is not a single part of the Sun that is cool enough not to be ridiculously hot.

-Eric

Image 1&2 Credit: Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams

Source: https://sdo.gsfc.nasa.gov/gallery/main/item/146, https://sdo.gsfc.nasa.gov/gallery/main/item/76

Further reading:

Take a look at the Solar Dynamics Observatory’s weekly image of the Sun: https://sdo.gsfc.nasa.gov/gallery/potw/latest

Here NASA talks a bit more about the history of sunspots: https://image.gsfc.nasa.gov/poetry/workbook/sunspot.html

This originally appeared on our sister page The Universe

The shergottites are as old as we thought they were!

This photo is a very tiny piece of Mars, viewed in a number of different ways. It is a grain of a mineral called baddeleyite, taken at high magnification using electron microscope techniques. Note the scale bar – 5 μm is about 1/5 to 1/10 the thickness of a human hair. This mineral deserves a special highlight today because this tiny grain, and a few others from the same rock, have settled a major ongoing debate regarding the martian meteorites.

The most abundant type of martian meteorite is a type called a shergottite. They make up more than ¾ of the martian meteorites available on Earth today, and, although there are some chemical differences, they look like normal igneous rocks that you’d find on Earth. They’re a rock type called basalt, and they look like they could have come out of a volcano on Hawaii or Iceland; islands almost totally made of basalt.

The shergottites were the first meteorites recognized to come from Mars. When scientists realize they’re holding a rock as unique as these, one of the first things they do is age-date the rock by measuring the abundances of radioactive elements and the products of radioactive decay.

There are a bunch of different radioactive elements that can be used to date a rock, including Potassium, Samarium, Lutetium, Rubidium, etc. When researchers measured the ages of the shergottites using those elements, they kept getting ages under 500 million years, sometimes as young as 100 million years old.

For Mars, those ages really are fascinating. Mars is much smaller than Earth and might have cooled off faster. Igneous rocks 100 million years old or younger means that the volcanoes on Mars have been active recently and may still erupt today.

There is, however, one problem with those ages. Every rock that has come to Earth from Mars has been blasted off the planet in a large impact. The energy released in that impact can disrupt and melt the rocks, and consequently the dates for the meteorites have large errors in them. Oftentimes, the different isotope clocks disagree by more than 100 million years.

And, there was one really big problem. The Uranium-Lead decay system is the most commonly used dating system for rocks in the solar system, but when used on martian rocks, that system gave ages over 4 billion years old. The U-Pb system disagrees with every other clock we have.

There are some reasons to believe the U-Pb system could be the one messed up. The other clocks work on rocks from the Moon, so we know they aren’t always disturbed by impacts. Also, the U-Pb system was being used on whole rocks rather than single minerals, and whole rocks can be contaminated by the environment. If lead was able to move around in surface waters on Mars, as does happen on Earth, it could have contaminated these rocks and just made any U-Pb age meaningless. But, even with that caveat, many researchers believed the shergottites must be over 4 billion years old based on the lead ages.

What would be really nice is to find a mineral with enough uranium and lead to date, since single minerals are much harder to contaminate than whole rocks. On Earth, the favorite mineral is zircon, which takes uranium into it, but there aren’t big zircons in these meteorites.

That leads to baddeleyite, which has the molecular formula ZrO2. Uranium substitutes for zirconium in this mineral, so it could work. Until recently, grains needed to be large to date, but recent work at UCLA has finally developed techniques to date grains this size.

Working with the labs at UCLA, a team of researchers led by the University of Western Ontario found these tiny baddeleyite grains in a martian meteorite from Africa (NWA 5298 is the official name) and, based on zoning that shows up in image box B, verified that the baddeleyites actually grew from a magma; the lines you see in image B wouldn't be preserved if it grew after the impact. But, there are tiny zircon layers on the edges of the baddeleyite, and those zircons were grown in the impact (they have perfect structure, demonstrated by the pattern in image D, which shows sharp bands indicating that the zircon has a normal structure and grew after the impact).

When the researchers dated the baddeleyites using the U-Pb system, they found that they were 187 million years old, exactly as old as we thought the shergottites were. Even cooler, they dated the zircon rims and found that they grew about 22 million years ago; possibly giving the date this rock was launched from Mars.

Finally we have a uranium-lead age for Mars that agrees with every other age we have for Mars. This is great, it means we actually know what we’re talking about! Also, it means the volcanoes on Mars have been active recently, within the last 100 million years, and the mantle of Mars is still active as well. A cooling mantle and active volcanoes can supply heat to the planet’s crust, and if there ever was life on Mars, could supply raw materials and heat that could even keep it going deep underground.

This is really important research about these rocks, if for no other reason than it confirms that we know what we’re talking about; the shergottites are as young as we thought they were, and that is just one more reason that Mars is a very interesting place.

-JBB

Press report: http://www.sciencedaily.com/releases/2013/07/130724200607.htm

Original paper and Image Credit, shared here for non-commercial purposes as permitted in Nature website use rules: http://www.nature.com/nature/journal/v499/n7459/full/nature12341.html

How do we know these rocks are from Mars? TU Post: https://www.facebook.com/photo.php?fbid=497017653696745&set=a.433415610056950.106382.334816523250193&type=1&relevant_count=1

Fast Flag

Just a tiny July 4th reminder – this tiny little flag is currently nearly 33 AU from the Sun and moving at a velocity of 14.5 kilometers per second relative to the Sun.

In exactly 10 days, this little flag will make its closest approach to the Dwarf Planet Pluto. This photo captures the side of the New Horizons Spacecraft as it appeared a decade ago…before this spacecraft launched on one of the longest voyages to its target ever taken by an Earth-built spacecraft.

-JBB

Image credit: NASA http://solarsystem.nasa.gov/news/display.cfm?News_ID=47793

Read more: http://pluto.jhuapl.edu/Mission/Where-is-New-Horizons/index.php https://twitter.com/Alex_Parker

Incoming!

Do you live anywhere near the lines on this map of the globe? If so, on May 8, give or take a few hours, you may have to, well, duck.

On April 27th, a Russian Soyuz spacecraft launched carrying a Progress supply capsule headed for the International Space Station. The spacecraft was carrying thousands of kg of food, supplies, and equipment, in addition to fuel to drive the spacecraft and the mass of the spacecraft itself.

The initial parts of the launch went fine, but as the spacecraft was approaching the final part of its launch the signals received on the ground from the spacecraft became intermittent and within a few hours they were lost completely. Russian engineers continued to try to contact the capsule and the capsule got close enough to the ISS to be visible by the astronauts, but the capsule itself has remained silent for over a week.

Unable to burn its engines or correct its course, the capsule is now in a decaying orbit around Earth. It needs to burn its engines to move higher and reach the ISS; instead, friction with the atmosphere is now causing the spacecraft to slow down and descend towards Earth.

Sometime late this week the capsule will re-enter Earth’s atmosphere and come down. The exact time is difficult to project as it is influenced by solar activity; a more active sun actually causes the upper layers of Earth’s atmosphere to rise higher and increases the friction on orbiting objects. Engineers worldwide can make educated guesses about when and where it will come down and narrow it down to within a few orbits, but that leaves error bars of several hours and most of the planet.

As the capsule enters the atmosphere it will break apart and much of the material inside will burn up due to friction, but several large parts of the capsule are likely strong enough to make it to the surface. Estimates suggest about 20% of the mass, likely over 1000 kg, will come down on the surface in an area potentially hundreds of kilometers wide.

Based on these orbits it is estimated that there is a 60% or so chance of it entirely hitting water, which is conveniently very close to the percentage of Earth’s surface covered by water anyway. The odds of it hitting a major, populated area are of course low, but this is not a game when we’d like to play the odds very often.

Hopefully Russian engineers are able to prevent problems like this on future missions, because this is actually really bad. The Space Station is well supplied enough that the loss of this spacecraft only costs money; the astronauts should be able to survive there with no issues assuming no more supply capsule failures in the near future, but uncontrolled descent of large metal objects is something we’d really like to avoid.

-JBB

Image credit: Spaceflight101 (used with permission) http://www.spaceflight101.com/progress-m-27m-re-entry.html#update

Read more: http://www.tsenki.com/en/launch_services/help_information/launch/2015/?EID=120974 http://space.stackexchange.com/questions/9042/can-we-see-the-russian-progress-59-spacecraft-burn-up-on-reentry

The Final Delivery

It’s not easy to get to the Planet Mercury. Any spacecraft sent into the inner solar system from Earth tends to pick up speed as it approaches the sun forcing a spacecraft to slow down in order to enter Mercury orbit, so just figuring out the path of the spacecraft is tough. On top of that, the environment around the sun is rough: featuring radiation bursts, solar wind, and high temperatures.

THE EARTH STORY NEEDS YOU! Nominations are open for the Fifteenth Annual Weblog Awards (Bloggies). The non-profit blog awards have been presented since 2001; they are the longest running and one of the largest blog awards. We'd love your nomination for either the Best Education Weblog, Best Topical Weblog and/or Weblog of the Year. Note: every nomination requires three nominees.  We proudly suggest our fans vote for: The Earth Story on Facebook (https://www.facebook.com/TheEarthStory) The Earth Story on Tumblr (http://the-earth-story.com/) and our sister page: The Universe (https://www.facebook.com/AstrophysicsAndAstronomy?fref=ts) Vote/nominate here http://2015.bloggi.es/ Entries close February 1, 2015. Loz

Large asteroid to pass Earth today Later today, probably while I’m still sitting in an airport trying to find a way to get to#Goldschmidt2014 (so far United has delayed me by ~10 hours, followhttps://twitter.com/TheEarthStory for conference tweets), a very large space rock is going to pass fairly close to Earth. There is no danger but it provides a number of good lessons. This asteroid is a potentially hazardous asteroid named 2014 HQ124. In the name of an asteroid, the first number gives the year it was discovered; in this case, 2014. The first detail you should notice is that this potentially hazardous, near-earth asteroid was only discovered in April of this year. In 2009, NASA launched the WISE spacecraft, a telescope that used infrared light to survey a large fraction of the sky. Objects like asteroids radiate light at these wavelengths, so the WISE telescope discovered a lot of them, both in the asteroid belt and closer to Earth. After its main mission ended, the mission was renamed NEOWISE and focused on discovering asteroids close to Earth that could be impact hazards. Unfortunately, the telescope was put into hibernation in 2011, but following the explosion of an asteroid above Chelyabinsk Russia last year, $5 million a year was redirected to turn the telescope back on and resume the search for potentially hazardous asteroids. 2014 HQ124 was identified in April by this telescope, and subsequent observations characterized its size and orbit. The asteroid was estimated to be ~325 meters in diameter (over 1000 feet) and later today will pass about 1.25 million kilometers from Earth. That’s about 3x the distance between the Earth and the Moon. For scale, this asteroid is probably about 10x the size of the rock that created Arizona’s meteor crater. If it hit Earth, it would cause an explosion equivalent to the detonation of about 2000 megatons of TNT (20 times larger than the biggest nuclear detonation ever). On average, a rock this size hits Earth about once every 100,000 years. To stress what I said several times, this asteroid will miss Earth by a lot today. It will be 3x as far from us as the Moon is. But there are lessons to take here. First, this asteroid is a Near Earth Asteroid (NEA) capable of producing enormous damage and it was just discovered this year. It is regularly stated that >90% of the asteroids larger than 1 kilometer capable of hitting Earth have been discovered, but rocks of this size are capable of doing significant damage to Earth and this one wasn’t discovered until very recently. Rocks this size pass within this range of Earth once every few years. A 600 meter rock will pass about 3 Lunar Distances from Earth next January. But, these passes should still serve as a reminder that we sit, to some extent, in a shooting gallery. It takes resources like WISE, money, and potentially other facilities in the future to find and track these objects. Until the Chelyabinsk explosion, the resources put into this problem were limited. They’re non-zero now, but finding these dangerous rocks is still an effort that will take years to decades at current rates. Furthermore, there’s no guarantee that, as memory of the Chelyabinsk explosion fades, the political will and funding to find these objects won’t fade with it. There will also be opportunities for science in this pass. Most of the time, these asteroids appear as points of light in the distance to telescopes, but the closer they get to Earth the more we can see. Facilities like the giant Arecibo observatory in Puerto Rico will observe this asteroid as it passes and in the case of Arecibo, it will use radar to determine the shape and other properties of the object. The more we observe objects like these when they do pass, the better we will be at understanding what they’re made of, how they behave in their orbits, and potentially in the future what we could do to deflect them. There will be several webcasts of the pass of this object from these observatories; details can be found at http://www.slooh.com/. For whatever reason, this object seems to have been nicknamed “the Beast” in popular media. The Beast isn’t going to hit Earth today, but it is both an opportunity to do interesting science and a reminder of what else is out there. -JBB Image credit: P. Carrill, ESA. http://newswatch.nationalgeographic.com/2014/06/05/watch-as-the-beast-asteroid-sails-past-earth-this-week/ Read more: http://www.weather.com/news/science/space/beast-massive-near-earth-asteroid-flyby-20140606 http://www.space.com/26148-beast-asteroid-flyby-earth-impact-scenario.html http://www.space.com/26129-beast-asteroid-near-earth-flyby-webcast.html http://www2.jpl.nasa.gov/sl9/back2.html http://impact.ese.ic.ac.uk/ImpactEffects/ https://twitter.com/AmyMainzer/status/460872564839952384/photo/1

OMG we might be right! When the Apollo program returned samples from the Moon, the rocks clearly differed from rocks on Earth. Different minerals, different abundances of minerals, clearly different histories and chemistries, but there were also surprising links between the two bodies. Oxygen is the most abundant atom in the Earth, making up nearly half of the planet’s mass. Oxygen has 3 isotopes with masses 16, 17, and 18. Modern instruments can measure the ratios of these 3 isotopes in rocks and one key observation is that almost every object in the solar system has a different mixture. Mars is different from the Earth, the Earth is different from meteorites, meteorites from one asteroid differ every other asteroid. But there was one exception; to within error, the Earth and the Moon matched.  This match was a big deal at the time and still is today. Since oxygen is so abundant it’s impossible to get a match by random chance: it’s like mixing 8 different types of pop at a soda fountain and coming out with the same exact mixture 2 times in a row.  Out of this data was born the idea that the Moon was formed by a giant impact into Earth. Late in Earth’s history ~50 million years after the planet started forming, an object at least the size of Mars, if not bigger, slammed into the Earth, spraying debris into orbit around the planet. That debris came together under gravity to form the Moon. That model could explain the Moon’s chemistry; identical to Earth in its oxygen isotopes but slightly different in its chemistry since it formed in a different way. The model fits many other parameters, like where the Moon formed, the ages of the Moon rocks, and why the Earth spins at the rate it does, so it is a very good model. But there was a problem. To understand how a giant impact could occur, scientists used advanced computer simulations to model how the energy and mass moved around during the impact (described here:https://www.facebook.com/TheEarthStory/posts/556021494458899). While doing this, they noticed something odd; the Moon kept being formed mostly out of material from the impactor.  There was a lot of exchange of mass between the two bodies since most of the mass of the moon was literally vaporized by the impact, but some parts of the impactor, known as Theia, should have been big contributors to the Moon. If this is the case, then how in the world could the Moon’s oxygen isotopes match the Earth so perfectly? Well, today we have the answer. Over time, we’ve been able to measure oxygen isotopes more precisely as better instruments are developed, and better measurements can detect smaller differences. New research just published in the journal Science by a team from Georg-August-University ät Göttingen measured rocks from the Moon and Earth at the best resolution ever done and found the tiniest of differences! This is about as exciting of a measurement of an incredibly tiny difference as we can get. This measurement fits with exactly what the people who developed the Giant Impact model for the Moon’s formation have been predicting and have been unable to explain for years. There should be tiny differences between the Moon and Earth if the Moon was splashed off of the Earth in a giant impact, and scientists finally just found one! Maybe, just maybe, we’re actually right! How cool is that! -JBB Image credit: http://www.nasa.gov/multimedia/imagegallery/image_feature_1454.html Original paper: http://www.sciencemag.org/content/344/6188/1146 Commentary: http://www.nature.com/news/lunar-rock-chemistry-supports-big-smash-theory-1.15356#/b1