February 6 – The Sky’s A Rockin’!

Today’s factismal: Nearly 42,000 meteorites hit the Earth every year.

Odds are, you’ve seen the really cool dashboard video of the meteor that light up the sky in Illinois and Wisconsin last night. Right now, we don’t know much about this particular meteor other than it was big and bright. We don’t know if it landed somewhere on Earth like the 42,000 other meteorites than come to ground each year or if it headed back out into space like the The Great Daylight Fireball of 1972. We’re not even sure where it came from – was it a piece of a comet or a chunk of an asteroid?

The Great Daylight Fireball of 1972 (Image courtesy and copyright James M. Baker)

The Great Daylight Fireball of 1972 (Image courtesy and copyright James M. Baker)

What we do know is that there will be nearly 70 different chunks of rock and ice that speed by the Earth in February alone! They’ll zoom past at distances ranging from just outside the atmosphere to 78 times the distance to the Moon. They range in size from the size of a tiny house (about 36 ft) to the size of a tiny village (about a mile across). These rocks are made up of chunks of comets and asteroids and even bits of Mars and the Moon that have been blasted into space by impacts from other chunks of rock!

A meteor streak across the Milky Way (My camera)

A meteor streak across the Milky Way
(My camera)

What is important about these chunks of rock is that they tell us how dynamic our Solar System is. Instead of being a dead old system with an orbit for everything and everything in its orbit, the Solar System is a dynamic, ever-changing system with the planets and comets and asteroids interacting to change orbits and thrown new stuff in new places. And they can provide us with samples from other planets and from the earliest formation of the system. Besides which, they are just plain pretty!

A meteorite as seen from above the atmosphere  (Image courtesy NASA/Ron Garan)

A meteorite as seen from above the atmosphere
(Image courtesy NASA/Ron Garan)

But the best thing about meteor is that you can help scientists learn more about them! If you download NASA’s Meteor Counter App (available for iPad, iPhone, and iWannaMeteor), then you’ll be able to send NASA scientists valuable information on the number of meteors that hit during the shower. They’ll then use that information to help us understand how likely it is that we’ll get hit. To learn more, go to NASA’s web site:
http://science.nasa.gov/science-news/science-at-nasa/2011/13dec_meteorcounter/

January 9 – Miss Demeter

Today’s Factismal: Ceres was first thought to be a comet.

Most astronomy fans know Ceres by reputation if not by name. It is the largest body in the asteroid belt, that loose pile of rubble that never quite coalesced into a real planet back when the Solar System was being built. It is small enough that you could it would take 78 chunks of rubble the size of Ceres to build one Moon. But what most astronomy fans (and other folks) don’t know about Ceres is that it has caused trouble for astronomers from the day it was found – and continues to cause trouble today!

When Giuseppe Piazzi first observed Ceres in 1801, he called it a comet. But Johan Bode decided that it was in the right place to be the “missing planet” he was looking for between Mars and Jupiter, and so he called it a planet and gave it an astronomical symbol. Unfortunately for Ceres, astronomers soon discovered over a hundred more “missing planets” in the same neighborhood, and they took to calling it a minor planet (astronomers get upset whenever there are more than ten planets; nobody knows why) when they didn’t call it an asteroid (astronomy speak for “tiny little star-like thingamabob”). And then, when yet more Pluto-sized objects were found in the outer Solar System, Ceres was reclassified yet again as a dwarf planet (see the previous note about astronomers and numbers bigger than ten).

An image of Ceres, taken by the Hubble Space Telescope

An image of Ceres, taken by the Hubble Space Telescope

Even its name is a subject for debate. In America, it is known as Ceres, for the Roman goddess of the harvest. But the Greeks have never consented to that name; they prefer to call it Demeter (which causes all kinds of confusion as there is another asteroid known as 1108 Demeter). And the Germans prefer to call it Hera for reasons that are inscrutable to anyone but a German.

Ceres as seen by the DAWN probe (Image courtesy NASA)

Ceres as seen by the DAWN probe
(Image courtesy NASA)

What is not in doubt is that Ceres is large enough to be shaped into a ball by its gravity, and that it has an interior that is divided into an icy outer part, a rocky middle section, and a metallic core (i.e., meets the definition of planet for everyone but the IAU). It is also possible that Ceres has an inner ocean between the outer icy part and the rocky middle; this is exciting because it makes Ceres one of the few places in the Solar System where life as we know it could exist. Ceres’ size and shape tell us that it is a relic of the early days of the Solar System, when everything was collapsing into small bodies that then collided to form the planets. So we can add planetismal and protoplanet to Ceres’ list of appellations.

The layers of Ceres, as we now know them. We expect to learn a lot more about Ceres once DAWN arrives there in 2015. (Image courtesy NASA)

The layers of Ceres, as we now know them. We expect to learn a lot more about Ceres once DAWN arrives there in 2015. (Image courtesy NASA)

Right now, the DAWN spacecraft is orbiting Ceres. Planetologists (i.e., the folks who still classify Pluto as a planet) are studying the asteroid in order to learn more about how planets form and develop over time, and to see evidence of the early history of the Solar System. They’ll also compare Ceres, which is the largest asteroid, with Vesta, which is the second largest and was visited by DAWN in 2013. As part of the NASA mission, JPL has launched the Asteroid Mappers website, where you can help to identify features on Ceres and Vesta:
http://dawn.jpl.nasa.gov/DawnCommunity/asteroid_mappers.asp

November 30 – Map Quest

Today’s factismal: The first map of the Moon was made 407 years ago today.

Back in the 1600’s, there were only two things that everyone was sure of: death and the fact that things in the heavens were perfect. The first was kind of obvious thanks to smallpox, war, famine, and straight party ticket voting, and the second had to be true because Aristotle said it and the Roman Catholic Church believed it. At the time, it was thought that anything on Earth was corrupt thanks to Adam’s sin while anything in the skies was part of Heaven and therefore incorruptible. So you can imagine the furor when Galileo took the telescope he invented and turned it to the Moon – and then told everyone what he saw.

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

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

And what he saw was revolutionary. Instead of being a perfect, smooth sphere, the Moon was covered with pockmarks and scars – what we know now to be impact craters and lava flows. While today all of the attention is given to Galileo’s proofs that the Earth was not the center of the Universe, it was his demonstration that the heavens were imperfect that struck the most direct blow at the Roman Catholic Church’s philosophy. As a result, even though anyone could verify the truth of Galileo’s work by simply looking, many preferred not to do so lest they also fall into heresy.

Galileo's map of the Moon (Image courtesy Galileo)

Galileo’s map of the Moon
(Image courtesy Galileo)

If you aren’t afraid of heresy then go out to look a the Moon tonight and take a long gander at the big black splotch that’s looking back at you. That’s Oceanus Procelarum, or the Ocean of Storms. It was named in 1655 (46 years after Galileo published his map) by Giovanni Riccioli, a Catholic priest who liked Galileo’s results but not his methods. To “punish” Galileo and his friends for disproving Church doctrine, he used the names of those who supported the heliocentric universe for the craters nearest Oceanus Procellarum which turns out to be one of the largest outflows of lava anywhere in the Solar System. That big white blotch on the eastern side of the stormy ocean? That’s Copernicus Crater, named for the chief heliocentricist and all-around troublemaker; those long white streaks are bits of lunar rock and dust that were thrown out when the asteroid slammed into the Moon and formed the crater.

A modern view of the Moon (Image courtesy NASA)

A modern view of the Moon
(Image courtesy NASA)

And while you may not believe it, we are still naming things on the Moon today! Even after four centuries of discoveries, there are still new features to see on the Moon and new things to identify. By mapping every crater and every lava flow and every mountain, we can get a better idea of how the Moon has changed over time and learn more about how the Solar System formed. And the best part is that you can help! Just head over to Cosmo Quest and start clicking on the Moon pictures to tell them what you see. For more information, land at:
https://cosmoquest.org/x/?application=simply_craters

November 14 – Supermoon!

Today’s factismal: Not all full moons happen when the Moon is closest to the Earth.

There’s a good reason that they call it “rocket science” (OK, actually they call it “astrophysics”); figuring out what is happening in the sky is hard. That’s because things are moving all around and interacting with each other in all sorts of weird ways. Let’s take something simple for example – the Earth-Moon-Sun system. You’d think that with just three bodies orbiting each other there would be an exact mathematical description of how things will move. And you’d be wrong! Though we can solve certain special cases, in general we cannot tell how the motion of the three bodies will change more than a short time into the future (a million years or so).

The Sun, Earth, and Moon, drawn to scale (almost - the Moon is three times as large as it should be)

The Sun, Earth, and Moon, drawn to scale (almost – the Moon is three times as large as it should be)

But we can tell some things for sure. For example, we know that a full moon happens when the Moon and Sun are on the opposite sides of the Earth. And we know that the Moon’s orbit around the Earth is not a perfect circle; instead it is an ellipse that slowly moves around the Earth. Since an ellipse has a part that comes closer to the Earth and a part that is farther away, sometimes the full moon happens farther away from the Earth and sometimes it happens closer. Things being what they are, most of the time the full moon happens farther away. But when it happens close to the Earth (what astronomy wonks call perigee {“close to Earth” in Greek}), we get a Supermoon.

The Earth-Moon system, draw to scale. Notice how the Moon's orbit is slightly elliptic.

The Earth-Moon system, draw to scale. Notice how the Moon’s orbit is slightly elliptic.

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How super is a Supermoon? Not very. Because the Moon’s orbit is an almost perfect ellipse, the Supermoon is only about 14% larger than a normal full moon. Unless you are very, very observant you’ll never notice the difference. You can see the exact difference in the images below. This first image shows a full Moon over China, taken by Expedition 48 Commander Jeff Williams on the ISS. The second image shows what a Supermoon would look like.

A full Moon over China (Image courtesy Expedition 48 Commander Jeff Williams, NASA)

A full Moon over China
(Image courtesy Expedition 48 Commander Jeff Williams, NASA)

What a Supermoon would look like

What a Supermoon would look like (Modified image)

Now even though the Supermoon isn’t spectacular, that doesn’t mean that the Moon isn’t special. It is our nearest neighbor and can tell us a lot about how the Earth and the rest of the Solar System formed. If you’d like to get in on the fun of discovering more about the Moon, then head on over to Moon Mappers where folks just like you are telling scientists what they see on the super-duper Moon!
https://cosmoquest.org/x/science/moon/

October 14 – Tone Deaf

Today’s factismal: Scientists have taken radio recordings from the Juno probe and turned them into sound recordings.

Jupiter is more than the biggest planet in our Solar System. It was Jupiter’s four largest moons that caused us to rethink our place in the Universe. It was Jupiter’s interaction with Saturn that moved many of the planets where they are today – and which continues to shape the Solar System even now. And, at 318 times the mass of Earth, Jupiter represents 70% of the non-Sun stuff in the Solar System. In other words, Jupiter is pretty darn important.

Jupiter, known to the Babylonians as Marduk (My camera)

Jupiter with its Galilean moons
(My camera)

Despite that, only nine probes have visited Jupiter – and only two of those orbited the planet! The first probe was Pioneer 10, which sped by Jupiter on December 4, 1973. It was followed a year later by Pioneer 11. Jupiter wouldn’t get another visitor until Voyager 1 and Voyager 2 used it as a gravity slingshot to get into the outer Solar System in 1979. It would take another 24 years before the Galileo mission would send a spacecraft to orbit Jupiter and drop a probe into the atmosphere. The spacecraft orbited Jupiter for eight years before being sent into Jupiter’s atmosphere in order to avoid accidentally contaminating any of the moons. Both Ulysses (in 2000) and Cassini-Huygens (in 2007) would fly by Jupiter to use its gravity but neither would do any detailed science. It wasn’t until last month that Jupiter got another orbiter: Juno.

An artist's deception of what Juno looks like orbiting Jupiter (Image courtesy NASA)

An artist’s deception of what Juno looks like orbiting Jupiter
(Image courtesy NASA)

Named after Jupiter’s wife, Juno was designed to orbit Jupiter and peer beneath its clouds to learn what was going on in the planet’s interior. (In mythology, Juno could peer behind the clouds Jupiter raised up to hide his mischief.) And one of the ways that Juno does that is with the Waves instrument, which listens to the radio signals given off by Jupiter and its aurora. They’ve just released their first results and they are pretty darn spectacular.

The instrument captured the sound made by the solar wind as it hits Jupiter’s magnetosphere (the region controlled by Jupiter’s magnetic field)  and slows down; it also captured the difference in radio energy inside of Jupiter’s magnetosphere and outside of it (where the Sun’s magnetic field rules). By listening to the sounds made by the data, scientists can learn how Jupiter’s magnetic field is structured which may help us build better magnetic devices here on Earth for things like fusion or radio broadcast.

Jupiter in real color (Image courtesy NASA)

Jupiter in real color
(Image courtesy NASA)

Now if you’d like to learn more about the Juno mission or help with mission planning, why not head over to JunoCam? They are looking for pictures from amateur astronomers and comments from everybody to help them plan the mission. To learn more, orbit:
https://www.missionjuno.swri.edu/junocam/

October 10 – Mad, Mad Moon

Today’s factismal: 3753 Cruithne was discovered in 1986 orbiting near the Earth.

Back in 1986, the search for Near Earth Asteroids was just getting started. And one of the first objects that they found was an oddball that they named 3753 Cruithne (pronounced “CREW-eee-nuh”; it is the name of a Pictish king).Why is it so odd? Well, for one thing, it is in a 1:1 resonance with the Earth; what that means it that it takes the same amount of time to go around the Sun that the Earth does. But because it has a highly elliptical orbit, sometimes it is far away from the Earth and sometimes it is very near. (Well, not that near; at its closest, 3753 Cruithne is thirty times farther away than the Moon.)

A plot of the orbits for 1,400 of the Near Earth Asteroids; 37 Cruithne is in there somewhere (Image courtesy NASA)

A plot of the orbits for 1,400 of the Near Earth Asteroids; 3753 Cruithne is in there somewhere
(Image courtesy NASA)

Because 3753 Cruithne has a regular relationship to the Earth, some folks refer to it as a “second moon” even though it isn’t. The confusion happened because astronomers love to think about what things look like, especially orbits. And when you look at 3753 Cruithne’s orbit, something amusing (to the astronomers) orbits. If you flew above the Sun and watched 3753 Cruithne orbit, you would see it moving out toward Mars and back in toward Venus, crossing Earth’s orbit twice on each trip. And, thanks to the odd shape of 3753 Cruithne’s orbit, it actually takes about a year to complete each go-round. It would look something like this:

3753 Cruithne's orbit as seen from above the Sun (Image courtesy Jecowa)

3753 Cruithne’s orbit as seen from above the Sun
(Image courtesy Jecowa)

But if you stand on Earth and watch 3753 Cruithne orbit, it looks much different. Because Earth passes 3753 Cruithne in its orbit, it appears that the asteroid is making a “horseshoe” in space. So the astronomers giggled for a while about some asteroids being close enough for horseshoes and left it there. Which is where the internet found it. Unfortunately, most of the people on the internet aren’t astronomers. (You are shocked, I know.) As a result, they don’t know that the horseshoe “orbit” of 3753 Cruithne only happens when you look at the asteroid from the moving Earth; that it is a geocentric view. Since we know that the heliocentric view is much closer to reality, using a geocentric one to claim that an asteroid is the Earth’s second moon makes about as much sense as claiming that the Sun orbits the Earth. And 3753 Cruithne is hardly the only asteroid to look like it is orbiting Earth when it isn’t; in 2014, 2014 OL339 was shown to also have a horseshoe orbit.

When viewed from Earth, it appears that 3753 Cruithne orbits us (as does everything else) (Image courtesy Jacowa)

When viewed from Earth, it appears that 3753 Cruithne (and everything else) orbits us
(Image courtesy Jecowa)

But that isn’t to say that the Earth doesn’t have a second moon every once in a while. (This is where life gets even more interesting than the internet thinks it is.) Due to the odd orbital interactions of all of the various bits of junk out there, every so often a small asteroid will get trapped in orbit around the Earth for a few days or a few weeks or a few years. When this happens, Earth truly does have a “second moon”; because these asteroids aren’t trapped by Earth’s gravity and are just “passing through”, they are referred to as coorbiting asteroids. In 1999, asteroid 2003 YN107 began a coorbit of Earth that lasted for seven years. And some experts estimate that we have a small, temporary “second moon” almost all the time!

The path of Earth's true

The path of Earth’s true “second moon”
(Image courtesy NASA)

So why aren’t we sure about how often the Earth has a “second moon” (even if it never is 3753 Cruithne)? Simply because asteroids are small and space is vast. As anyone who has ever tried to find a remote control in a room has discovered, it can take a long time to locate something if it is very small compared to the room that you are looking in. But having more people looking can help. And that’s where you can join in on the fun! The Asteroid Survey is looking for folks who are looking to be looking for asteroids! (Here’s looking at you, KD!) You’ll sort through photos, identifying objects as stars, asteroids, or “junk”. And you’ll be helping to identify the millions of bits of junk that fly through our Solar System and give us our second moons. To join in on the fun, orbit over to:
http://www.asteroidzoo.org/

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!
http://lunarscience.nasa.gov/citizen-science/