Universe Today

March 13, 2012December 23, 2015 by Fraser Cain

Watch This 3D Printer Make a Microscopic Car

3D printing of a microscopic race car. Image credit: TU Vienna

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3D printers let you manufacture any 3-dimensional object out of plastic. You just download the design, fire up the old 3D printer, fill the hopper with plastic, and it’ll slowly print out the object. It sounds cool, and hackers are having a great time playing around with them, but it still doesn’t compare to the scale, quality and cost of traditional manufacturing. It’s still a toy for hackers… right?

As you know, technology has a way of creeping up and then dramatically changing everything. And once you watch this mind-bending video of an ultra-high-resolution 3D printer creating a tiny race car, I think you’ll agree with me that 3D printing technology is improving in leaps and bounds.

Researchers at the Vienna University of Technology recently demonstrated a new kind of 3D printer that can create objects orders of magnitude faster than previous devices, at much finer scales; just a few hundred nanometers wide.

Check out this amazing video of the new 3D printer technology quickly creating a microscopic model of a race car.

Their printer uses a liquid resin which is hardened at exactly the right spots by a focused laser beam (rule 1, everything cool is done with lasers). The lasers can be redirected by mirrors and can harden a line of this liquid resin just a few hundred nanometers wide, giving it a very high resolution.

But it’s also fast. In the past, 3D printers were clocked at millimetres per second. Well, this TU Vienna printer can harden a 5-meter line of resin in 1 second.

There were two discoveries that pushed this advance forward:

They improved the control mechanism of the mirrors so they’re in continuous motion, accelerating and decelerating at the precise times to get the high resolution printing.
They used photoactive molecules to harden the resin. When the laser light hits the resin, it induces a chain reaction that turns it from a liquid to a solid; only at the point of highest intensity.

What would you use a 3D printer like this for? If it’s this fast and accurate, the mind boggles with the possiblities. The researchers proposed medical applications, like building scaffolding for living cells to attach, allowing you to grow organs in the lab. But the imagination really breaks down trying to imagine the implications for this kind of technology.

Okay, now I want one.

Original source: TU Vienna, with a nod to SpaceRef.

March 13, 2012December 23, 2015 by Jason Major

Huge Coronal Hole Is Sending Solar Wind Our Way

SDO AIA 211 image showing a large triangular hole in the Sun's corona on March 13

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An enormous triangular hole in the Sun’s corona was captured earlier today by NASA’s Solar Dynamics Observatory, seen above from the AIA 211 imaging assembly. This gap in the Sun’s atmosphere is allowing more charged solar particles to stream out into the Solar System… and toward Earth as well.

Normally, loops of magnetic energy keep much of the Sun’s outward flow of gas contained. Coronal holes are regions — sometimes very large regions, such as the one witnessed today — where the magnetic fields don’t loop back onto the Sun but instead stream outwards, creating channels for solar material to escape.

The material constantly flowing outward is called the solar wind, which typically “blows” at around 250 miles (400 km) per second. When a coronal hole is present, though, the wind speed can double to nearly 500 miles (800 km) per second.

Increased geomagnetic activity and even geomagnetic storms may occur once the gustier solar wind reaches Earth, possibly within two to three days.

The holes appear dark in SDO images because they are cooler than the rest of the corona, which is extremely hot — around 1,000,000 C (1,800,000 F)!

Here’s another image, this one in another AIA channel (193):

latest_1024_0193 — AIA 193 image of the March 13 coronal hole

Keep up with the Sun’s latest activity and see more images on NASA’s SDO site here.

Images courtesy NASA, SDO and the AIA science team.

March 13, 2012December 23, 2015 by Fraser Cain

Jupiter’s Jet Streams Get Thrown Off Course

Jupiter's jet streams. Image credit: NASA/JPL/SSI

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Both Earth and Jupiter have jet streams; fast-moving winds that circle the globe. On Jupiter, those jet streams are constrained to very specific bands of the planet, while they meander around the Earth. We can see huge variations of weather when Earth’s jet streams move around – like unusually cold weather in Florida.

These strange weather patterns can occur on Earth when the jet streams interact with another atmospheric phenomenon called Rossby waves. We have them here on Earth, and they were first identified on Jupiter about 20 years ago.

And now scientists have identified the signature of Rossby waves throwing the jet streams off course on Jupiter. During its flyby of Jupiter, NASA’s Cassini spacecraft captured these images of Jupiter’s atmosphere; 100 were stitched together into a time-lapse movie.

If you watch the movie, you’ll be able to see a series of small, dark, V-shaped “chevrons” forming along the side of the jet stream. Eventually the well-defined atmospheric band starts to ripple and distort because of these Rossby waves. This shows that the jet streams on Jupiter, like Earth, can be thrown off course by the Rossby waves.

Here’s a quote from the press release:

“A planet’s atmosphere is a lot like the string of an instrument,” says co-author Michael D. Allison of the NASA Goddard Institute for Space Studies in New York. “If you pluck the string, it can resonate at different frequencies, which we hear as different notes. In the same way, an atmosphere can resonate with different modes, which is why we find different kinds of waves.”

By studying these waves, scientists hope to be able to get an idea of what lies beneath Jupiter’s thick cloud layers; to understand the deeper atmospheric composition and structure.

Original source: NASA/JPL/SSI News Release

March 13, 2012December 23, 2015 by Fraser Cain

Who Discovered Mercury?

Mercury's limb. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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Mercury is one of the 5 planets visible with the unaided eye. Even thousands of years ago, ancient astronomers knew that the 5 wanderers were different from the other stars in the sky. The 5 planets visible with the unaided eye are Mercury, Venus, Mars, Jupiter and Saturn. They gave them distinct names, and charted their positions with incredible accuracy. It’s impossible to say “when was Mercury discovered”, since that would have been before recorded history.

But when did astronomers realize that Mercury was a planet? That happened with Copernicus developed his model of a Sun-centered Solar System, published in 1543. With the Sun at the center of the Solar System, and not the Earth, it meant that both the Earth and Mercury were planets. This discovery was confirmed when Galileo first turned his telescope on the planets and realized they matched predictions made by Copernicus. Unfortunately, Galileo’s telescope wasn’t powerful enough to reveal a disk for Mercury, but it did show how Venus went through phases like the Moon.

This model was backed up by Galileo, who pointed his first rudimentary telescope at Mercury in the 17th century. Unfortunately his telescope wasn’t powerful enough to see Mercury go through phases like he saw with Venus.

Because it’s so small and close to the Sun, Mercury was difficult to observe with ground-based telescopes. More powerful telescopes only revealed a small grey disk; they didn’t have the resolution to display features on the planet’s surface, like craters or lava fields.

It wasn’t until the early 1960s when radio astronomers started bouncing signals off the surface of Mercury that more information was finally known about the planet. These signals revealed that Mercury’s day length is about 59 days. Even more detailed observations have been made with the Arecibo telescope, mapping surface features down to a resolution of 5 km.

The most detailed observations of Mercury have come from the exploration from spacecraft sent from Earth. NASA’s Mariner 10 spacecraft swept past Mercury in 1974, capturing images from an altitude of just 327 km. It eventually mapped about half of the planet in unprecedented detail, revealing that the planet looked very similar to the Earth’s moon, with many impact craters and ancient lava fields.

If you’re wondering who discovered the element mercury, nobody knows that either. The element has been known for thousands of years, and was used by the ancient Chinese. Liquid mercury was found in Egyptian tombs closed up almost 4,000 years ago.

We have written many articles about Mercury for Universe Today. Here’s an article about new mysteries unveiled on Mercury, and the possibility that Mercury could cause an interplanetary smash-up.

Want more information on Mercury? Here’s a link to NASA’s Solar System Exploration Guide, and here’s a link to NASA’s MESSENGER Mission Page.

We have also recorded a whole episode of Astronomy Cast that’s just about planet Mercury. Listen to it here, Episode 49: Mercury.

References:
NASA Cosmic Distance Scales
NASA Solar System Exploration: Mariner 10

March 13, 2012December 23, 2015 by Fraser Cain

Shock Diamonds

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I recently reported on Chinese plans to launch Shenzhou-9, and used a stock image of a Long March-2F rocket blasting off the launch pad. Nafin wanted to know what that diamond pattern trailing behind the rocket was, and ivan3man_at_large posted the answer: they’re called shock diamonds.

Shock diamonds? That term had somehow slipped past me, so I thought I’d dig into it some more.

Shock diamonds (alternatively known as “Mach disks”) occur when gas is exiting a nozzle at supersonic speeds, at a different pressure than the outside atmosphere. At sea level, the exhaust pressure might be lower than the thick atmosphere. And then at very high altitudes, the exhaust pressure might be higher than the thin atmosphere.

So these shock diamonds can appear just as a rocket is taking off, or at high altitude when it shifts into supersonic speed.

A classic example is the space shuttle blasting off, but another famous example is when Chuck Yeager’s X-1 rocket plane reached Mach 1.

Let’s take the example of a rocket blasting off. In this case, the exit pressure of the exhaust is lower than the outside atmosphere, and so you get a situation called “overexpansion”. The gas exits the rocket at a lower pressure, and fans outward from the exhaust nozzle in an “expansion fan”. But the outside atmosphere is higher pressure than the exhaust gas, and so compresses it inward. This difference in pressure forces the gas back together at a specific point – the first shock diamond.

(I’ll spare you all the complex fluid dynamics at this point.)

Then the gas compensates and expands again into a new expansion fan, and then it’s forced back together the same distance further along from the rocket at the next shock diamond, and so on and so on. Eventually atmospheric distortion and friction takes over, equalizing the pressure of the exhaust plume with the ambient atmosphere.

Shock diamonds behind the SR-71 Blackbird.

Shock diamonds were originally discovered by Ernst Mach, the famous Austrian scientist who did work on fluid dynamics.

One other interesting side note, shock diamonds aren’t just seen in rocket exhausts. They’ve also been seen blasting out of volcanoes and artillery guns

There are two great articles on Mach diamonds if you really want to understand them more deeply. Check out this article from Aerospace Web and this one from the Allstar Network.

March 13, 2012December 23, 2015 by Fraser Cain

Venus-Jupiter Conjunction, March 15th, 2012

The two conjunctions. Image credit: Stellarium

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In case you’re the only person on Earth who hasn’t heard about it yet, Venus and Jupiter will be in conjunction on March 15th, 2012, passing within 3° of each other. The two planets have been getting closer and closer in the sky for the last month, and now it’s time to see them side-by-side. Venus is the higher, brighter object, and Jupiter is the lower dimmer one.

Of course, Venus and Jupiter aren’t actually close to one another in the sky. They’re really separated by millions of kilometres. But from our perspective here on Earth, we see the two objects closely lined up. That’s a conjunction.

On March 15th, 2012 at 10:37 UTC, Venus and Jupiter reach 3° distance from one another. That’s approximately 6 times the width of the full Moon.

And in case you’re wondering, the conjunction will be visible from everywhere on Earth: from Australia to Canada, from Japan to Chile. The two planets will brighten in the West shortly after sunset. Since Venus and Jupiter are two of the brightest objects, they’ll be visible even in the most light polluted cities.

As a special bonus, the planet Mars is also high and bright in the sky, visible as that bright red “star” further to the East. Mars recently reached its closest point to Earth, known as opposition. Mars won’t be this close and bright for two more years.

Venus/Jupiter/Moon conjunction 2012 Image credit: Fraser Cain

The sky show will continue, and on March 25th, 2012, the New Moon will join the pair again to create a triple conjunction. Another great photo opportunity. Here’s our photo gallery of images Universe Today readers sent in during the last Moon/Venus/Jupiter conjunction.

Although 3° sounds close, they can actually get much closer. In October 26, 2015, for example, the two planets will only be 1° apart. But this is one of the best conjunctions we’ll see for a few years because the two planets are so high in the sky after the Sun sets.

We’d love to see your pictures of the conjunction. Please email them to [email protected], and we’ll post them in a few days.

March 12, 2012December 23, 2015 by Fraser Cain

Next Chinese Mission Might Include Some Women

Long March rocket launching the Shenzhou 5. Credit: Wikimedia

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Officials from the Chinese Space Agency announced today that they’ve completed crew selection for their next team of spacefarers – called taikonauts – and this time, the team includes some women.

The next major mission for China will be the first manned docking mission to the Tiangong-1 space station. This station was launched in September 2011, and was successfully docked with the unmanned Shenzhou-8 spacecraft back in November.

And so the next major step in the Chinese plans is for Shenzhou-9 to perform a manned docking with the station. Three taikonauts will be on board, and that crew might include some women – the first time the Chinese will have sent women to space.

This mission is already progressing nicely. The Shenzhou-9 spacecraft and its Long March-2F rocket have been completed. And if everything goes as planned, they’ll launch and perform the manned docking some time between June and August 2012.

The final composition of the Shenzhou-9 crew hasn’t been announced yet, so it might still be a few more years before the Chinese women finally get their chance to fly to space.

Original Source: Xinhua

March 12, 2012April 26, 2016 by Fraser Cain

Why Does the “Man in the Moon” Face Earth?

The two sides of the Moon. Image credit: LRO

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When we look at the Moon, we see these amazing variations of light and dark. And depending on your orientation on Earth, you might see the famous “Man in the Moon”, or maybe the “Rabbit in the Moon”. The darker areas are known as maria, smooth lava fields created by ancient volcanic eruptions on the Moon.

But why do we see this face of the Moon, and not a different side?

The Moon’s rotation is tidally locked to the Earth. This means that the Moon always presents the same side to us, completing one orbit around the Earth in the exact same amount of time it takes to turn once on its axis. From our perspective, the Moon never rotates, always displaying the “Man in the Moon”.

And before the space age, it was assumed that the entire Moon looked like this. When the first spacecraft were sent from Earth to orbit the Moon, they sent back surprising photographs that revealed a completely different landscape from what we’re used to. Instead of the dark splotches of lunar maria we see on the near side – the “Man in the Moon” – the far side is merely covered in craters.

So why is the maria-side facing us, while the crater-side faces away? Is it just a coincidence?

Researchers from the California Institute of Technology think that it’s not about luck at all, but the way the Moon’s rotation slowed down after its formation. Oded Aharonson, a professor of planetary science at Caltech, and his team created a simulation that calculated how the rotation of the Moon slowed down after its formation.

Although the Moon looks like a sphere, it actually has a slight bulge. And billions of years ago, when the Moon was rotating much more quickly, showing its entire surface to the inhabitants of Earth, the Earth’s gravity tugged at this bulge with each rotation, slowing it down slightly each time until the Moon’s rotation was completely stopped from our perspective.

In every simulation that the Caltech did, thanks to the orientation of this lunar bulge, either the Moon’s maria-side or crater-side ended up facing Earth. But the rate at which it slowed down – how fast it dissipated its rotational energy – defined our chances of seeing the “Man in the Moon”.

If the Moon slowed down quickly, it would have been a 50/50 chance. But because the Moon slowed down more gradually, we had a much higher chance of seeing the maria-side as the final result. The maria-side was twice as likely to be our final view over the crater-side. The results of this research was published in the February 27th edition of the Journal Icarus.

You can read a more detailed article from the Caltech news release.

March 12, 2012December 23, 2015 by Fraser Cain

Life Will Always Find a Way… To Eat Everything

A type of worm from the Dorvilleids family. The first known species to consume Archaea.

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A couple of consumption stories crossed my desk today, so I thought I’d merge them together. The bottom line is that everything’s on the menu. If there’s energy to be extracted from something, life is going to find a way to consume it.

We’ve got a deep sea worm that seems to be able to thrive from any of the three main branches of life on Earth – the first known example of a creature that consumes Archaea.

And then there’s the discovery of a fungus capable of consuming large amounts of polyurethane plastic.

Eating from all three branches of the tree of life

The first example of this comes from research done at Oregon State University about a single-celled microorganism called Archaea. This class of life is one of the three basic “domains of life” on Earth, including bacteria and eukaryota (multi-celled creatures like us).

Scientists believed that Archaea were completely disconnected from the food web – the circle of life just didn’t include them – but researchers at Oregon State University tried feeding two varieties of Archaea to a type of deep sea worms that live near the “black smoker” vents off the coast of North America.

To their surprise, these worms were perfectly happy eating Archaea, as well as standard meals of bacteria, spinach or rice. They grew at the same rate, regardless of what branch their food was hanging from on the tree of life.

That brings new meaning to the term “omnivore”.

Scraping fungus off a tree in Ecuador. Image credit: Yale University

Next up, a fungus that will eat your plastic.

Researchers from Yale University have discovered a variety of fungi in the Amazon Rainforest (where else?), that can “eat” a common form of plastic known as polyurethane. This, of course, would be the holy grail of recycling, since there’s no natural process that will get rid of plastic.

While exploring the Amazon, they discovered a fungus in the rainforest of Ecuador and brought it back to the lab for analysis. They experimented with it a bit and discovered just how quickly it could consume plastic. In one report, the fungus was only 10 days old and had significantly consumed about a quart’s worth of plastic – without needing any oxygen.

The puzzling part, of course, is trying to figure out what this fungus normally eats in the wild, since it’s not growing on plastic trees.

Here’s more info on the plastic gobbling fungus.

March 12, 2012December 23, 2015 by Fraser Cain

Atmosphere of Mercury

A High-resolution Look over Mercury's Northern Horizon. Credit: MESSENGER team

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When you look at an image of Mercury, it looks like a dry, airless world. But you might be surprised to know that Mercury does have an atmosphere. Not the kind of atmosphere that we have here on Earth, or even the thin atmosphere that surrounds Mars. But Mercury’s atmosphere is currently being studied by scientists, and the newly arrived MESSENGER spacecraft.

Mercury’s original atmosphere dissipated shortly after the planet formed 4.6 billion years ago with the rest of the Solar System. This was because of Mercury’s lower gravity, and because it’s so close to the Sun and receives the constant buffeting from its solar wind. Its current atmosphere is almost negligible.

What is Mercury’s atmosphere made of? It has a tenuous atmosphere made up of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor. Astronomers think this current atmosphere is constantly being replenished by a variety of sources: particles of the Sun’s solar wind, volcanic outgassing, radioactive decay of elements on Mercury’s surface and the dust and debris kicked up by micrometeorites constantly buffeting its surface. Without these sources of replenishment, Mercury’s atmosphere would be carried away by the the solar wind relatively quickly.

Mercury atmospheric composition:

Oxygen 42%
Sodium 29%
Hydrogen 22%
Helium 6%
Potassium 0.5%
With trace amounts of the following:
Argon, Carbon dioxide, Water, Nitrogen, Xenon, Krypton, Neon, Calcium, Magnesium

In 2008, NASA’s MESSENGER spacecraft discovered water vapor in Mercury’s atmosphere. It’s thought that this water is created when hydrogen and oxygen atoms meet in the atmosphere.

Two of those components are possible indicators of life as we know it: methane and water vapor(indirectly). Water or water ice is believed to be a necessary component for life. The presence of water vapor in the atmosphere of Mercury indicates that there is water or water ice somewhere on the planet. Evidence of water ice has been found at the poles where the bottoms of craters are never exposed to light. Sometimes, methane is a byproduct of waste from living organisms. The methane in Mercury’s atmosphere is believed to come from volcanism, geothermal processes, and hydrothermal activity. Methane is an unstable gas and requires a constant and very active source, because studies have shown that the methane is destroyed in less than on Earth year. It is thought that it originates from peroxides and perchlorates in the soil or that it condenses and evaporates seasonally from clathrates.

Despite how small the Mercurian atmosphere is, it has been broken down into four components by NASA scientists. Those components are the lower, middle, upper, and exosphere. The lower atmosphere is a warm region(around 210 K). It is warmed by the combination of airborne dust(1.5 micrometers in diameter) and heat radiated from the surface. This airborne dust gives the planet its ruddy brown appearance. The middle atmosphere contains a jetstream like Earth’s. The upper atmosphere is heated by the solar wind and the temperatures are much higher than at the surface. The higher temperatures separate the gases. The exosphere starts at about 200 km and has no clear end. It just tapers off into space. While that may sound like a lot of atmosphere separating the planet from the solar wind and ultraviolet radiation, it is not.

Helping Mercury hold on to its atmosphere is its magnetic field. While gravity helps hold the gases to the surface, the magnetic filed helps to deflect the solar wind around the planet, much like it does here on Earth. This deflection allows a smaller gravitational pull to hold some form of an atmosphere.

The atmosphere of Mercury is one of the most tenuous in the Solar System. The solar wind still blows much of it away, so sources on the planet are constantly replenishing it. Hopefully, the MESSENGER spacecraft will help to discover those sources and increase our knowledge of the innermost planet.

We have written many articles about Mercury’s atmosphere for Universe Today. Here’s an article about how magnetic tornadoes might regenerate Mercury’s atmosphere, and here’s an article about the climate of Mercury.

If you’d like more information on Mercury, check out NASA’s Solar System Exploration Guide, and here’s a link to NASA’s MESSENGER Misson Page.

We have also recorded an entire episode of Astronomy Cast all about atmospheres. Listen here, Episode 151: Atmospheres.

References:
NASA: Atmosphere of Mercury
NASA Solar System Exploration
Wikipedia
Nature.com