January 25 – Hot Topic, Cool Science

Factismal: IRAS was launched on January 25, 1983.

Astronomy entered a new age in 1983, with the launch of the Infrared Astronomy Satellite, or IRAS for short. IRAS wasn’t the first telescope into space, nor was it the first infrared telescope. But it was the first infrared telescope in space. And that is what matters, because it turns out that space is the place to be if you want to see something that is invisible.

The InfraRed Astronomical Satellite (IRAS) discovered the first exoplanet (Image courtesy NASA)

The InfraRed Astronomical Satellite (IRAS) discovered the first exoplanet (Image courtesy NASA)

You see, the part of the spectrum that we see is just a very, very limited part of a much wider whole. The visible spectrum, which covers the colors from blue through red, says a lot about the world. But the invisible spectrum, which covers colors that are cooler than red (the infrared) and hotter than blue (the ultraviolet), tells us a lot more about the universe. Part of that is simply because most of the universe is very, very cool. And the rest is because the parts that aren’t cool can be very hot indeed.

The hotter something is, the

The hotter something is, the “blue-er” its color is

And it turns out that the temperature is the key to the color. Back in 1900, Planck was able to show that the color of an object was intrinsically related to its color. For example, the Sun is yellow because the part of it that we see is about 5000 K (about 8540 F, or “really, really hot”). We now use that principle in a number of ways, from taking the temperature of a star to taking the temperature of a baby.

But not all colors of light make it through to the ground. To understand this, think of a brick wall. You cannot see through a brick wall because the bricks block the visible light while allowing more energetic gamma rays to pass through. Similarly, our atmosphere blocks a substantial part of the infrared light while letting the more energetic visible light through. And, just as you can see what’s on the other side of a brick wall by walking around it, telescopes can see the infrared colors blocked out by our atmosphere by going above it.

And when they did, what an amazing array of interesting things they saw. While looking at over 500,000 light sources, IRAS discovered the source of the Geminid meteor shower. IRAS discovered six new comets. IRAS saw the dust created by asteroid collisions as a giant cloud surrounding the Solar System. And IRAS saw 75,000 different galaxies with huge numbers of new stars being born. Most importantly, IRAS gave us the first picture of planets forming from a cosmic cloud of dust and gas.

And the hits from IRAS keep coming, even though the satellite quit working nearly thirty years ago. That’s because there are lots and lots of images from IRAS and other space telescopes that need people to look through them. People just like you! If you’d like to try your hand at classifying infrared images, then try the Milk Way Project:

November 28 – Red Headed Menace

Today’s factismal: There have been 55 probes to Mars since the first one launched 52 years ago today.

Back in 1964, the US and the USSR had one thing in common – neither one of them could get a spacecraft to Mars. The two countries were engaged in a space race, trying to show that they could do more and go further than the other but all of their probes to Mars failed. The USSR had launched five different probes to Mars, only one of which had made it out of Earth orbit. The US had launched just one probe but the cover on it had failed to separate, meaning that the probe couldn’t make it to Mars. And then came Mariner IV.

A close-up of a crater on Mars (Image courtesy NASA's HiRISE)

A close-up of a crater on Mars
(Image courtesy NASA’s HiRISE)

Based on the successful Ranger probes that had explored the Moon, the Mariner was designed to take photos of Mars’ surface and send them back to Earth; it also would measure cosmic rays in space, look for changes in solar wind and plasma, and discover how much dust was in the Solar System. All of these things would be important if we were ever to travel to Mars. At 2:27:23 PM UTC on November 28, 1964, atop an Atlas missile with an Agena booster, the Mariner probe headed for the skies and then for Mars. It would fly past the Red Planet 228 days later and send back the first close-up images ever taken of the planet.

The first close-up picture of Mars (Image courtesy NASA)

The first close-up picture of Mars
(Image courtesy NASA)

Today there are eight different probes in orbit around or exploring the surface of Mars. They are telling us about its climate, its atmosphere, its composition, how it has changed over time, and (most importantly) if it has life living below its surface. And the best part of the exploration of Mars is that you can be a part of it. Just fly over to Planet Four: Terrains and tell them what you see in each image (craters, sand dunes, little green men). The scientists will use your classifications to help them understand how Mars has changed over the years. To learn more, land on:

September 2 – An Ill Wind

Today’s factismal: The lightning in a Category 1 hurricane has enough power to run a house for more than 300 years.

If you read the news today, you know that Hurricane Hermine has come aground in Florida. This ended the long dry spell for hurricanes damaging the US mainland (though Sandy was a hurricane in 2012, it had been downgraded to tropical storm before it came ashore); it was the first time in eleven years that the US mainland was hit. Of course, you don’t have to get a hurricane to get lots of storm damage, just ask the folks who sat through Sandy or Allison. Although it is too early for firm estimates, experts think that the damage from this storm will end up costing the US at least $5 billion.

A satellite image of Hurricane Sandy showing the temperature differences in the clouds (Image courtesy NASA)

A satellite image of Sandy showing the temperature differences in the clouds
(Image courtesy NASA)

So what causes all of that damage? The short answer is “energy”. Hurricanes are nature’s way of taking heat from the equator (where it is hot) and moving it to the poles (where it is cold). They do that by using the heat to evaporate water, which forms clouds, which forms storms. Because that heat also causes the air to expand, it drives winds which can drive water in the form of storm surge. Add it all together and you’ve got a lot of energy moving around, looking for something to break – like Florida.

Hurricane Hermine making landfall in Florida (Image courtesy NOAA)

Hurricane Hermine making landfall in Florida
(Image courtesy NOAA)

But how much of the storms energy is released by the different parts of a hurricane’s life cycle? Scientists have run the numbers and found that a hurricane typically releases about 0.002% of its energy as lightning. Now that may sound like small potatoes, but for a Category 1 hurricane, it works out to be enough energy to run a typical household for 360 years or so. (The trick is catching the lightning.) Storm surge is what does most of the damage along the coast and yet it is just 0.02% of the total energy of the hurricane. The winds in a hurricane are what creates that lightning and tornadoes and other exciting side-effects. They are understandably much more powerful; they represent about 4% of the total energy in a hurricane. Interestingly, the sheer weight of the water falling from the sky as rain and hail releases about as much energy as the wind does. Thus far we’ve accounted for about 9% of the energy in a hurricane with the lightning and the storm surge and the winds and the rain. Where is the rest?

Some of the effects of a hurricane (Image courtesy NOAA)

Some of the effects of a hurricane
(Image courtesy NOAA)

It is released high in the sky as water vapor condenses into rain drops and is known among meteorology wonks as the latent heat of vaporization (which is just a fancy was of saying “the heat stored {latent} in vapor”). As the water vapor is carried higher into the atmosphere by the rising air currents, conditions change so that water vapor is no longer stable and water is; this is what forms clouds (which are just raindrops that are too small to fall). When the water condenses, it gives back some of the energy that was used to turn it into a gas; the rest of the energy has gone into raising the vapor high into the sky and powering all of the other special effects.

But here’s the odd thing. Even though we can use satellites to track hurricanes and help people get out of their way, we still don’t know how reliable our satellite images of the clouds that make up hurricanes are. And that’s where you come in. NASA has a citizen science program called S’COOL that asks for people like you and me to tell them what clouds are out there when the satellites pass by. To participate, float on over to:



August 23 – Far Sighted

Today’s factismal: Galileo demonstrated the telescope to the public for the first time 407 years ago today.

It isn’t often that someone invents one device that literally changes the way we see the Universe; what is exceptional about Galileo is that he invented two devices that did it. In 1625, he invented a occhiolino (“little eye”) that allowed him to explore the world of the miniscule; at a dinner in his honor, one of his students gave the device the name that we now know it by: the microscope (“seer of little things”). But that wasn’t his first foray into optics, nor his most famous. For that invention, we need to step back to August 23, 1609, when Galileo revealed his telescope (“seer of distant things”).

Galileo's telescope revolutionized our view of the Universe - literally!

Galileo’s telescope revolutionized our view of the Universe – literally!

Though there were field glasses before Galileo, they had limited magnification and blurry images. Worse, the poor quality glass caused rainbow rings to show around everything. Galileo got around these problems by using several lenses in series to adjust the image bit by bit. This method is still used today in binoculars and other optical devices.

Jupiter and three of its moons, as seen through a modern camera (mine)

Jupiter and three of its moons, as seen through a modern camera (mine)

Once Galileo had invented his telescope, he turned it onto the sky and saw nothing but trouble. One of the first things he saw was Jupiter and four bright points of light that circled around it. By the end of the week, he had proven that these small starry messengers revolved around Jupiter. Being a savvy sort, he published his findings in Sidereus Nuncius, a short treatise that was dedicated to Cosimo II de’ Medici and called the four moons of Jupiter “Medicean stars”. We now know them as Europa, Ganymede, Callisto, and Io and call them the Galilean satellites.

Before Galileo, nobody knew that the Moon had craters (image from my camera)

Before Galileo, nobody knew that the Moon had craters (image from my camera)

His invention literally changed the way we see the universe, but his discovery did so figuratively. Under Aristotle’s view of the cosmos, the Earth was the center and everything revolved around it. Things in the heavens were perfect and pure, and were in heaven because they were pure and perfect. Because the ideology fit so well with the dogma of the Catholic Church, it was adopted as Church Law – to challenge it was to challenge the very essence of belief. Though some troubling differences had arisen between the pure circles demanded by Aristotle and the observed paths of the planets, these were smoothed over by Ptolemy’s “epicycles” of circles on circles. Questioning these ideas was dangerous at best and heresy at worst.

The Solar System as Copernicus saw it (and Galileo proved)

The Solar System as Copernicus saw it (and Galileo proved)

Galileo did worse than question them: he made it possible for anyone to see that he was right and the Church was wrong. By simply looking through the telescope, people could see everything that he discovered. They could see the moons of another planet. They could see the “jug-ears” of Saturn. They could see the phases of Venus. They could see the spots on the face of the Sun and the scars on the face of the Moon.

Galileo's sketch of Saturn

Galileo’s sketch of Saturn

Galileo was first rewarded for his discoveries and then punished for his hubris. He became a superstar in Pisa, and other city-states wooed him, trying to get him to move and to bring his beautiful ideas with him. But his ego led him to clash with others, making enemies out of supporters. Eventually, he was brought before the Inquisition for heresy and threatened with torture. He renounced his views and spent the rest of his life under house arrest. It would be 206 years before the Roman Catholic Church would take his works off of the banned list and 376 years before the Vatican would formally clear him of any wrongdoing.

Galileo's drawing of sunspots (Image courtesy The Galileo Project)

Galileo’s drawing of sunspots
(Image courtesy The Galileo Project)

In opening the heavens to us, Galileo laid the foundations of modern science. He showed that clear logic alone (Aristotle’s approach) is not enough. Logic must be backed with evidence and hypotheses must be checked against observations. If you would like to honor Galileo, there is no better way than in joining one of the citizen science groups that is classifying and naming features on the Moon!

August 9 – The Dead Planet

Today’s factismal: Mars has more surface area than all seven continents combined.

If you hang around JPL or the Russian launch center at Baikonur for any length of time, you’ve probably heard them talking about the Great Galactic Ghoul. According to legend, this monster hides out near Mars and lives off of the space probes that it eats. And what a diet it has had! Over the past five decades, the Great Galactic Ghoul has eaten about half of the probes sent to Mars. For example, on August 9, 1973, the USSR sent Mars 7, one of four different probes to Mars that they would launch that summer.  All four probes would be eaten by the Great Galactic Ghoul.

Percival Lowell's drawing of the martian canals (Image courtesy Percival Lowell)

Percival Lowell’s drawing of the martian canals
(Image courtesy Percival Lowell)

Of course, nobody actually thinks that there is a giant space monster out there eating our probes. (Well, maybe a few politicians.) The Great Galactic Ghoul just symbolizes how difficult it is to send a probe to another planet. So why do we keep doing it? In a word: science. By sending rovers and landers and orbiters to Mars, we can learn a lot about the planet. For example, we’ve learned that Mars is not covered with canals, that Mars is covered with ground water, and that there might be life on Mars (in the form of bacteria living deep in the soil).

The little rover that could; Opportunity has lasted twwelve long years on Mars (take *that* Mark Whatney!) (Image courtesy NASA)

The little rover that could; Opportunity has lasted twelve long years on Mars (take *that* Mark Whatney!)
(Image courtesy NASA)

But Mars is a planet with more surface area to explore than all seven continents combined. Thus far we’ve explored that enormous area with seven landers and four rovers supplemented with ten orbiters. That’s like saying that we’ve explored Earth by driving half-way from Washington DC to New York City while stopping at the Chicago, Albuquerque, and Moscow airports. Needless to say, there’s a lot left to explore.

A dust devil on Mars as seen by Spirit (Image courtesy NASA)

A dust devil on Mars as seen by the Spirit rover
(Image courtesy NASA)

And that’s where you come in. It turns out that one of the most important parts of planning a mission for a lander or rover is deciding where it should land. And in order to that the scientists need to look at every image of Mars’ surface taken by the Mars Reconnaissance Orbiter (MRO for short). But there are a lot of images to sort through. The MRO has three cameras and has been in orbit for a decade now; all told, it has taken more than 250,000 pictures of Mars’ surface. So the scientists need ordinary folks (that’s you) to look through the backlog of pictures and help them decide what they are looking at. Is it sand dunes? Is it flat plains? It is valleys? Or mountains? To take part, head over to Planet Four – just mind the Great Galactic Ghoul!


July 29 – Cold, Cruel Fate

Today’s factismal: Eris “the Pluto killer” was discovered eleven years ago.

One of the most contentious questions in science today is “What is a planet?” Scientists can (and do) argue over the question for hours at a time, mainly because how you answer it all depends on what characteristics you think are important for planets. Most notably, the International Astronomical Union (a body that was set up to keep us from arguing over names) famously decided that not only was Pluto not a planet, it wasn’t even related to “real” planets. Interestingly, they did this even though their own subcommittee said that Pluto should remain a planet and even though many planetologists consider Pluto to be one.

The Eris system (Image courtesy NASA)

The Eris system
(Image courtesy NASA)

But why was Pluto “killed”? Why did they decide that Pluto wasn’t a planet? It all starts with Pluto itself. When it was found, Pluto was so far away that it was just a dim light in the telescope. As a result, everything that we thought about Pluto was based on the other planets that were out there: Jupiter, Saturn, Uranus, and Neptune. All of those planets are big and gaseous (what planetologists call “jovian planets”), so the natural assumption was that Pluto was more of the same. But as telescopes got better, Pluto got smaller. It shrank from being the size of Jupiter to being the size of the Earth to being smaller than the Moon (for what it is worth, the planet Mercury is only a little larger than the Moon).

Pluto and its largest moon, Charon (Image courtesy NASA)

Pluto and its largest moon, Charon
(Image courtesy NASA)

And, as if that weren’t bad enough, we started seeing other objects out near Pluto that were about the same size as the planet itself. The most famous of these new planets was Eris, aptly named for the Greek goddess of discord, which was actually larger than Pluto. The astronomers then panicked over the prospect of having more than ten planets in the Solar System and led the IAU to redefine the word so that they wouldn’t have to quit using their fingers to count. (To be fair, this wasn’t the first time that the problem had arisen; it happened with the Galilean planets and with the minor planets.) As a result, Pluto and the other planets out there became known as “dwarf planets” (an appellation that was originally intended to apply to Earth).

A plot of planetary size versus density. Notice how Pluto ends up with the junk.

A plot of planetary size versus density. Notice how Pluto ends up with the junk.

But call it a dwarf planet, a KBO, or a giant cookie, Pluto is still out there.Even better, there are thousands upon thousands upon thousands of other planets out there, just waiting to be found! If you’d like to try your hand at discovering the next planet of discord, then why not head over to Planet Hunters? They’ve got tons of Kepler data just waiting for you!

May 17th – Baby I’m a Star

Today’s factismal: It is National Telecommunication Day. Go call your mother!

Today is National Telecommunication Day, celebrating 58 years of communicating with satellites. Amazingly enough, we are actually still communicating with the satellite that launched the telecommunications revolution. named Vanguard 1, it was launched on May 17, 1958 and was supposed to last just six years; it is now the oldest man-made satellite in orbit. This little wonder weighs just three pounds, is just over 6.4 inches across, and goes around the Earth nearly eleven times a day. Since it was put into orbit, it has seen more than 238,000 sunrises; if you go outside today, you might see it rise yourself.

An engineering spare for the Vanguard 1 satellite (Image courtesy NASA)

An engineering spare for the Vanguard 1 satellite (Image courtesy NASA)

Vanguard 1 had three main missions. The first, and most important, mission was restoring the nation’s confidence in their space program. Though the US had managed to launch a satellite into orbit (Explorer 1 on January 31), it had started to tumble almost right away. Worse, there had been several very public failures including one rocket explosion shown live on television. A successful launch was essential to demonstrate that the US could keep up in the “space race” that had developed.

An artist's deception of what Vanguard 1 looks like in orbit (Image courtesy NRL)

An artist’s deception of what Vanguard 1 looks like in orbit
(Image courtesy NRL)

Second, Vanguard was intended to bolster interest in science and engineering. In order to do that, it had two radio transmitters that broadcast on ham radio frequencies. Ostensibly, the beacons were intended to help geophysicists accurately determine the shape of the Earth by allowing them to measure the slight changes in Vanguard’s speed caused by changes in the topography below; practically, they encouraged young students to become engineers and scientists by allowing them to hear the satellite as it went overhead. (This mission is continued today with the AO-51, AO-27, and SO-50 satellites.) By communicating with people on the ground around the globe, Vanguard 1 started the telecommunications revolution that led us through the Echo 1 satellite,  (the first satellite dedicated to communication), Elvis’ Aloha From Hawaii (the first international live satellite concert with a single performer), and into today’s interconnected world.

Engineers working on the vanguard 1 satellite before launch (Image courtesy NASA)

Engineers working on the vanguard 1 satellite before launch
(Image courtesy NASA)

Vanguard 1’s third mission was also the most counter-intuitive to non-physicists. Vanguard 1 was intended to allow scientists to measure the density of the atmosphere in outer space. Though most non-scientists believe that there is a hard boundary between outer space and the atmosphere, in truth it is more of a vaguely defined zone. As you go up, the atmosphere becomes less and less dense but never entirely stops. As a result, satellites that orbit close to the Earth (e.g., Vanguard 1, the International Space Station) are slightly slowed down by atmospheric drag. By measuring the amount of slowdown, physicists are able to determine the density of the upper atmosphere.

Installing Vanguard 1 on the rocket that would take it into orbit (Image courtesy NRL)

Installing Vanguard 1 on the rocket that would take it into orbit
(Image courtesy NRL)

And the results were certainly surprising. Originally, the mission planners had thought that the upper atmosphere was so thin that the satellite would orbit for 2,000 years. Instead, it is dense enough that Vanguard 1 will fall to Earth after only 240 years (185 years from now). Those results have helped with the design of new satellites and even inspired one private space venture.

If you’d like to get a little inspiration of your own but don’t want to build a ham radio station, then why not use the SatCam app? This smartphone app uses pictures that you take of clouds to “ground-truth” satellite data so that scientists can get a better idea of what the satellites are really seeing. In return for your photos, the app shows you what the satellite saw as it passed overhead.