A Fragment of Muonionalusta

meteorite 5

This little chunk of crystalline metal is a tiny slice of a meteorite — a rock that fell from the sky. When one says that, the next natural question is, “how do you know it’s a meteorite?” (We will get to that.) But what is really staggering is not just that we know, but how much we know about it and its history. And what a long history it is.

This specimen is a 68 gram sample cut from a fragment of the Muonionalusta meteorite.  According to our best current understanding, the parent body that Muonionalusta came from was one of the earliest bodies to take shape during the formation of our solar system. It began as a protoplanet (or planetisimal) that accreted within the protoplanetary disk that would eventually become our solar system. It accreted over the course of roughly the first million years after the beginning or our solar system. (That is to say, during the first million years after the very first solids condensed from the protoplanetary disk.) The parent body had an iron-nickel “planetary” core, 50–110 km in radius, that was eventually exposed by collisions that stripped away most of its insulating mantle. It cooled very slowly over the next 1-2 million years. It is estimated (with startling precision) by Pb-Pb dating that the body crossed below a temperature of ~300 °C at 4565.3 ± 0.1 million years ago, just 2-3 million years after the solar system began to form. For the next four billion years, it led a largely unremarkable existence as an asteroid (minor planet) until it broke apart (possibly due to a major collision) about 400 million years ago. Then, one fine day roughly one million years ago, a large fragment entered the earth’s atmosphere, breaking into hundreds (perhaps, thousands) of smaller fragments that rained down in a shower of fire upon what is now northern Sweden and Finland. Four ice ages transported the surviving meteorite fragments across the Swedish tundra, until their first discovery (and naming after the nearby Muonio river) in 1906.

But, how do we know all of that?
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BAMF2014: A Cocktail Glass for Zero Gravity

BAMF 2014 175
Part of our continuing coverage of highlights from the 2014 Bay Area Maker Faire.

The Zero Gravity Cocktail Project from the Cosmic Lifestyle Corporation aims to make a cocktail glass suitable for drinking fluids in zero-G:

The Zero Gravity Cocktail Project is an attempt to bridge the gap between the space tourism vision and mainstream reality. By creating a fun object that appeals to many people, we hope to show that space tourism is not an abstract concept but a stepping stone for improving the way people live, work, and play beyond planet Earth.

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Fluids don’t behave the same in outer space, so a glass would have to have quite a different design, relying on capillary action not gravity to move them from point A to B. Channels guide the fluid from stem to rim.

These are 3D printed prototypes of white plastic. Future versions might be 3D printed from clear biocompatible plastic, or made of glass or stainless steel.

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The glass has bulbous bottom with a hollow stem, for balance and fluid delivery.  A rubber one-way valve can be inserted into the bottom to allow the glass to be refilled as you drink. They have also made an earthbound variant of this glass that has a more traditional base, allowing it to be set down, when gravity permits.

We’re secretly hoping that the next version includes a way to suspend your olive in the middle of the conical section, no toothpick required.

Meteor Alert for North America Tonight

2009 Leonid Meteor by Navicore

Photo by Ed Sweeney under CC-BY license.

From spaceweather.com:

METEOR ALERT: Sky watchers in North America might see an outburst of meteors during the early hours of June 11th when Earth passes through a stream of cometary debris last seen in 1930. Forecasters Peter Jenniskens (SETI Institute) and Esko Lyytinen (Helsinki, Finland) predict the return of the gamma Delphinid meteor shower this Tuesday morning around 08:30 UT (04:30 am EDT). The shower is expected to last no more than about 30 minutes with an unknown number of bright, fast meteors.

Comet Pan-STARRS

The Exploratorium writes:

The comet Pan-STARRS is currently in view! Did you glimpse it last night?

This beautiful photo was taken by Exploratorium Staff member Adam Esposito last night (March 12) from the Berkeley Hills with a telephoto lens. Uranus is actually right near the comet as well. Mars in the clouds below.

TO VIEW TONIGHT: most of USA and northern hemisphere should look west, about 30 minutes after sunset. You may be able to see it below the crescent moon. It’s close to the sun so only after sunset is it briefly visible in the darkening sky.

We were able to see it last night with a Galileoscope, in spite of haze and an aggressive tree-line, by locating the moon and panning left. SpaceWeather.com has a helpful sky map, too.

Curiosity on Mars!

NASA Ames

Congratulations to Curiosity! As the New York Times says this morning,

In a flawless, triumphant technological tour de force, a plutonium-powered rover the size of a small car was lowered at the end of 25-foot-long cables from a hovering rocket stage onto Mars early on Monday morning.

A crowd of some 5000 people gathered on the plaza at NASA Ames Research Center late last night (it was only Monday Morning on the east coast) to watch presentations by mission scientists and finally the live broadcast, on the big screen.

This was a thrill.  Not only was the landing process itself incredible— watch this video, “Seven minutes of terror” if you haven’t —but it was amazing to be in a crowd of so many people excited to watch the landing as well.  Many of the people in the audience screaming and cheering had worked on various parts of the mission, including the ground-breaking (pun intended) scientific instruments aboard the rover and the new lifting-body heat shield to get it there.

Curiosity closes in on Mars

On Sunday night, the Mars Science Laboratory rover Curiosity (the one on the right; the biggest, baddest, most awesomest Mars rover ever) will attempt to land on Mars. Curiosity is a nuclear powered Mini Cooper sized robotic geologist, much bigger and more capable than previous rovers. It’s going to be a moment of great excitement when Curiosity touches down, and there are a number of ways that you can watch.

If you have the opportunity (Mars rover pun intended) check with your local science museum, planetarium or hackerspace to find out if they’re hosting a viewing party.

Curiosity model at Exploratorium

Here in California, the Exploratorium currently hasa special exhibition up, including the simplified full-scale model of the rover in the picture above. They will be airing a live webcast of the landing on Sunday night.  And, NASA Ames Exploration Center in Mountain View, is hosting a live broadcast on-site with over 5000 people. The free tickets for the event went very quickly.

And, if you can only watch on the internet, NASA TV is NASA’s official video channel.  Star Talk Radio has a list of places to watch online. Space Industry News has a similar lineup, which includes a link to a google map of events.

Viewing the Transit of Venus

Transit of Venus with binoculars

Venus is just now passing between the earth and the sun, and so we stepped outside to take a look. We brought out a pair of binoculars to use to project the image of the sun onto a piece of paper on the ground. We also took a solar viewing film, but it turns out that the binoculars were a great way to see it as a group. These pictures were taken just after Venus crossed over the edge, and the speck you can see at the edge is much clearer if you click through to the large size on flickr. Over there, you may also be able to make out a couple of sunspots that we were also able to see with the binoculars, but not with the viewing film. Remember, don’t look directly at the sun without proper safety equipment! (See our earlier post for more details on viewing techniques.) The transit is still underway, so you still have a chance to get outside and see it!

Transit of Venus Closeup

 

Update:  Part II, with a slightly different method.

Venus Transit 3

To get a slightly better view, we used a simple telescope mounted to a tripod.

Aside: This is the Galileoscope, a high-quality, very low cost telescope for $50 (or as little $25 in classroom packs).  It’s designed to let you discover everything that Galileo could see with his telescope, including craters on the moon and the moons of Jupiter, albeit with modern optics that dramatically improve image clarity.

 

Venus Transit 2

Now, the one thing that you really don’t want to do with a telescope is directly look at the sun through it. (It’s bad enough to stare into the sun; it’s much worse to concentrate the light into a tiny spot.  That’s a good way to start fires, not view the Transit!)

What you can do is to project the light from the telescope onto a piece of paper or matte-white plastic. Adjust the focus until the edges are sharp and— poof! —suddenly, you can see the sunspots.

Venus Transit 1

And the image quality isn’t half bad.  This picture was taken right at the “peak” of the Transit, when Venus was as far into the disk of the sun as it went.  Our image on the screen is about two inches (five cm) across, and it’s easy to make out the features.

Most stunning of all is the incredibly rare opportunity to see a planet in the sky not just as a “point of light” but to see it for what it is: another planet just like ours, slowly orbiting around the same sun.

A Spectacular Speck on the Sun

Today, Tuesday June 5, 2012, the planet Venus— the planet in our solar system that is closest to the shape and size of Earth —will leisurely pass squarely between the Earth and sun.

The Transit of Venus, as it is called, is a once (or maybe twice) in a lifetime event. If at all possible, make an effort to see it today, because you won’t have another chance… at least until the year 2117.

While it will not be visible everywhere in the world (see map), it will be visible for all of North America, Asia, Australia, and eastern Europe. (The latter, towards sunrise on June 6.)   The transit begins at 22:09 UTC, peaks at 01:29 UTC, and ends at 04:49 UTC.  Here in the PDT time zone, that’s 3 PM, peaking at 6:30 PM, and finishing below the horizon. (More at the LA Times.)

Now, how to actually view it?

If you were clever, you might have stashed away an eclipse-viewing filter from the recent solar eclipse.  If not, another option— one that is cheap and easy to find at hardware stores —is a set of welding glasses with a #14 filter. (That’s black glass. Sadly, those dark green goggles that you found in the shed are likely not safe for direct solar viewing.)

But, as the Ontario Science Center warns you,

Be careful: there are many materials that may seem to block out the Sun’s rays, but which are not safe to use for solar viewing. DO NOT LOOK AT THE SUN THROUGH sunglasses, photographic neutral density filters, polarizing filters, photographic film, dark plastic such as garbage bags, or smoked glass.

 

The other approach to consider is indirect viewing. You can build a pinhole projector, or a simpler yet version.  You can also use a telescope set of binoculars to focus sunlight onto a surface for indirect viewing. (Using binoculars or a telescope for direct viewing requires a carefully chosen solar filter, to be safe.)

If all else fails— maybe you’re in cloudy Portland —NASA has got you covered. Head right over here for a “live” feed of solar pictures from the SDO spacecraft in orbit around the Earth, and updating every 15 minutes.

Update: A nice summary of the historical background of viewing transits of Venus is here.

[Image source]

Shadows of an Eclipse

Eclipse 2012- 5

There were a lot of amazing things that we saw this weekend at Maker Faire— everything from live demonstrations of snails creating artwork (by Presley Martin) to the DIY pick and place machine (from buildyourcnc.com).

There was also something special in the sky: the solar eclipse on Sunday.

Eclipse 2012- 9

Viewed elsewhere (e.g., further north in California) this was an annular eclipse, where the sun does not disappear entirely, but instead becomes a ring of fire (since the apparent size of the moon is not large enough to block the full disk of the sun).

For us at Maker Faire in San Mateo, it was a spectacular partial eclipse, which we were able to view through solar viewing filters, kindly handed out by the Exploratorium.


Eclipse 2012- 8

Of course, it turns out that you don’t actually need a solar filter to watch the eclipse. Any little aperture— in this case the cap between my hand and the camera —can act as the pinhole in a pinhole camera and project the image of the sun onto a surface.


Eclipse 2012- 4

Eclipse 2012- 2

So if you’re not sure if an eclipse has started, or how much of an eclipse it is, just hold out your hands and make some little apertures; the shadows will show up with little bright spots in the shape of the sun, whether that’s a circle, ring, or crescent.

Eclipse 2012- 1

Stranger yet is to look around at all the shadows that you see every day. Even the shadow of your hand takes on an unexpected shape when the sun is anything other than round.
There are actually five outstreched fingers on my hand here, but you can hardly tell that when every bit of light that seeps through (or around the edges) projects a crescent-shaped image.

We take for granted that the shadow of an object will the same shape as the object, but as you can see, that isn’t necessarily the case when the light source isn’t round.

On the dwarf planets

Pluto


When Pluto was “demoted” from being a planet some years ago, I thought that it was pretty stupid. After all, I had learned about our set of nine planets as a simple fact in grade school. If anything, I had expected the number of planets to grow as they were discovered, not shrink.

What’s the big deal? Why not just grandfather Pluto into the club? The principal consequence of which objects are called “planets” is how many little plastic balls go into a solar-system model kits, right?

Well, yes and no. It turns out that our solar system has a huge number of objects. Not just the sun and a handful planets, but also hundreds of thousands of other cataloged objects (“minor planets”), the vast majority of which are now classified as small solar system bodies. These include most of the main-belt asteroids, comets, centaurs, trojans, kuiper-belt objects, scattered-disc objects, and other trans-neptunian objects. And, we will discover more.

Today Pluto, like Ceres, is proudly known as one of our five wonderful dwarf planets.

What distinguishes these dwarf planets from their larger and more familiar cousins? An intuitive and powerful discriminator: Simply put, planets are out there orbiting on their own, while dwarf planets are found in belts of objects that share the same orbit. Putting this in mathematical terms, there’s a stark difference between our eight planets– which dominate their orbital neighborhoods –and our five known dwarf planets, which at best make up mere fractions of their respective belts. Now that we’ve recognized the difference between major planets and dwarf planets, it’s clear as day which group Pluto belongs to.

And, despite poor Pluto, the minor shame of having “lost” one of our planets seems more than made up by the discovery in 2003 of Eris– a dwarf planet both larger and (usually) more distant than Pluto. Already, some dozens of other dwarf planet candidates have been identified, and there are countless others yet undiscovered.

The simple fact is that we live in an exciting time of discovery. While it may feel natural in a sense to enshrine an immutable list of “the planets,” it is instead our humble duty as scientists to accept that we don’t — and almost certainly never will –know everything.