Quick link for you, KOMO’s Tom Hutyler and Jane Shannon interviewed me about the asteroid 2012 DA14 (close pass by the Earth on February 15 — no danger).

Hear it here: http://www.komonews.com/radio/home/featured/190111451.html

~ A l i c e !

An asteroid is going to miss the Earth by a somewhat narrow margin on February 15, 2013 at 11:25am Pacific Time.

What’s Special About This Asteroid Approach?

Closest “Ever”

Just like we keep finding water on Mars, internet commenters wax hyperbolic about the latest meme (“This is the best YouTube video EVAR!”), and we break a local weather record every three months, you can spin anything to be the most ever, the biggest ever, or the closest ever, as long as you add enough qualifiers.

In this case, this is the biggest object¹ to get this close to the earth², since we started doing regular sky surveys in the 1990s³ looking for objects like this. As much as I’ve just knocked down how exciting that is, this is pretty cool. It is going to be close enough to be almost visible.

1. Smaller objects have been closer. Meteors streak through our atmosphere every day.
2. This asteroid is coming in closer than our farthest satellites. In fact, it is closer than a big set of our satellites: the geostationary satellites. Other asteroids you’ve heard of approaching us have been just barely within the orbit of the Moon. Time for a picture or two:
   
   
   This is a small selection of satellites you use. There are hundreds of satellites in orbit around the Earth, though most of them fall into one of these illustrated orbits. I created the image above, the satellite drawings are not to scale, but the orbits, Earth, and Moon are. Jonas Goodwin drew the satellites for me. Click to make it big enough to read.

In the picture just above, the smaller green ring is the same as the larger grey ring (with the DirecTV and GOES satellite) in the “Satellites You Use” diagram above. This asteroid-orbit diagram is from NASA. Click to link over to their website and description.

3. Lucky for you and me, there are people out there looking for asteroids that are going to get close to the Earth. NASA’s Near Earth Object (NEO) program has got your back! Of course, they need more telescope time and more funding to do a complete survey, but they sure are finding a lot of these babies. I, for one, am happy they’re doing their jobs.

Reasonably-sized

2012 DA14 (also known as “this asteroid”) is about 50 meters wide. That’s half an (American) football field, or ten yards longer than the retired Space Shuttle.

According to NASA estimates, this size of asteroid gets close to the Earth about every 40 years, but only impacts the Earth once every 1200 years.

Seeing it

If you want to see this asteroid, your best bet will be to check out NASA’s Goldstone Radar results after February 20th, or search the internet for images obtained by some of the most talented amateur astronomers such as Thierry LeGault, who specializes in taking pictures of fast-moving dim objects.

Unfortunately, here in Seattle it won’t be above the horizon until daytime, so we’re out of luck.

Might 2012 DA14 Hit The Earth?

No.

“2012 DA14 will definitely not hit Earth,” emphasizes Don Yeomans of NASA’s Near Earth Object Program at JPL in the NASA press release of January 28, 2013. “The orbit of the asteroid is known well enough to rule out an impact.”

So, no.

Similar Events

This is the same size meteor that impacted the Earth creating Meteor Crater in Arizona (50,000 years ago), and the same size as the object that exploded just above the Earth’s surface during the Tunguska Event in Siberia in 1908. From these two events we know that a meteorite of this size is destructive, but not catastrophic to the whole world. Their disastrous effect was limited to a few hundred square miles. With notice, we can plan for evacuation of an area that large.

Want More?

NASA Press Release (well written)

Near Earth Object Program Homepage

My old post: Satellites You Use (to give you a sense of scale of where this asteroid is, where our satellites are, and where the Moon is, in relation to the Earth)

Meteor Crater

Tunguska Event (This is awe-striking, read about it)

~ A l i c e !

I think you can guess what spurred me to search out astronomy books appropriate for ages 0-2. That’s right, my daughter. Feel free to chime in with your favorites in the comments, but remember we’re talking about 0-2-year-olds here, so board books or simple text. Rhyming or rhythmic text is also good.

I was very unhappy when I found that the selection for 0-2-year-olds was quite limited. I liked several books out of what was available though. I’ve finished my first draft of a board book of my own, but until I find a publisher I’ll stick with recommending other people’s books.

Papa, Please Get the Moon for Me (Classic Board Book)

By Eric Carle — ISBN-13: 978-0689829598, Seattle Public Library, Amazon.

So far this is my daughter’s favorite of the books I got. I’m not surprised, because it’s by Eric Carle! I hesitate very slightly about recommending this one, because at the end it implies that the Moon actually changes size when it changes phase. But imagination is also important.

The board book has large flaps that are prone to being crunched by small hands. It’s a good book, anyway.

The Sun Is My Favorite Star

By Frank Asch — ISBN-13: 978-0152021276, Seattle Public Library, Amazon.

I love this one. The story is good, the pictures are clean and bright. It’s accurate and pretty.

Happy Birthday, Moon

By Frank Asch — ISBN-13: 978-0812448320, Seattle Public Library, Amazon.

Again, it’s an imaginative story, but stays correct in its scientific concepts. Moonbear can’t reach the Moon, but none-the-less is able to get the Moon a birthday present and give it. I think Frank Asch is one of my new favorite author-illustrators.

Curious George and the Rocket (Board Book)

By H.A. Rey — ISBN-13: 978-0618120697, Seattle Public Library, Amazon.

This is edited down from the non-board-book version (Curious George Gets a Medal), but somehow I don’t mind for this story. Monkeys always make a great story. And this one also has a countdown–lots of fun with the little ones.

Countdown! With Milo (The Adventures of Milo and Mouse)

By Mike Austin — ISBN-13: 978-1609052089, Amazon.

I love it! It’s a countdown… I already said those are great, and the pictures have so many things to point at and find, and “buttons” to “push.” (It’s a plain flat board book, no real buttons).

Space Station (Mini House Book)

By Peter Lippman — ISBN-13: 978-0761115755, Amazon, but it’s out of print

I know, it’s out of print, so it isn’t fair for me to suggest it. This is a book and a toy. You open the pages to look through the space station. So far, in our house, it’s been less of a book and more of a toy–which is fine by me. Literacy at this age involves just being comfortable with books as well as spending time reading them. So, even if you can’t find this one, you can look up other Mini House books.

Astronaut (Mini People Shape Book)

By Giovanni Caviezel and C. Mesturini — ISBN-13: 978-0764162169, Amazon.

Another toy-book. I definitely got this one for the shape. The text is a bit advanced for right now, it’s pretty much a collection of factoids. Fun anyway.

There’s No Place Like Space: All About Our Solar System Revised Edition (The Cat in the Hat’s Learning Library)

By Tish Rabe and Aristides Ruiz — ISBN-13: 978-0679891154, Seattle Public Library, Amazon.

I would be remiss if I didn’t talk about this book. Much to my surprise I liked it. If you don’t have a 0-2-year-old in your life right now you might think Cat in the Hat is great for young kids. A lot of the Seussian books are actually a bit advanced, and long for the 0-2 crowd. Toddlers are not quite ready for the puns; the rhyming and rhythm are great for them though. This book is good and accurate enough, the rhymes are fun. It is a “tour of the solar system” book, but it doesn’t harp on about getting through basic facts on each planet. It just goes through one or two cute topics for each. You might not read the whole book with your toddler in one sitting, but that’s okay.

~ A l i c e !

There was a bright green meteor streaking through the western sky over Seattle a couple hours ago (midnight-thirty-ish local time). Check out West Seattle Blog’s continuing coverage to hear some first-hand accounts.

This was a bolide meteor (an exploding meteor/shooting star). It was part of the Quadrantid Meteor Shower. Read my article about why we see meteors below if you’re interested in some of the science behind that.

Also, why colors? The same reason different fuels burn with different colored flames: it depends on the chemicals in the fuel. Green is commonly produced by copper when conducting flame/fireworks color experiments here on Earth–doesn’t mean the fireball had any copper in it, that’s just a related piece of information. It is also true that our eyes are very bad at determining colors at night–so the green could just be an optical illusion and not related to the composition of the meteor.

~ A l i c e !

You’ve already been hearing about how the ancient Maya didn’t predict the end of the world today, that’s just misinformation, so I thought I’d share some of my favorite accurate topics about the ancient Maya astronomy and mythology.

Dark Constellations

In western astronomy and western mythology we recognize constellations as dot-to-dot pictures made of stars. In other words, we make images out of “positive space” to use some art terminology. The ancient Maya are a completely different culture: several of their constellations are made of “negative space.” They recognize images in the dark spaces between the stars. Here is an enhanced image, you can easily see the llama across the middle (with a star for an eye), and the snake in the upper right-hand corner:

I always love to use this as an example of how “different cultures are different.” Just because we think dot-to-dot pictures are the “normal” way to do constellations doesn’t mean every other culture everywhere also thinks that.

Venus

The ancient Maya place extreme significance on the planet Venus. Their calculations of exactly when it will rise, set, first appear after sunset, last appear before sunrise rival even today’s computers. And they didn’t have computers. We should spend more time observing natural phenomena ourselves.

Calendar

Their calendar is AMAZING. It has cycles within cycles. There are several good java converters out there that show you how it works.

Also, when you see a picture of the “Maya Calendar” it should be laid out in a rectangle. If it is in a circle and looks like a compass rose it is most likely the Aztec Calendar. (If it looks like gears cycling within each other, it might be the Maya Calendar after all).

Sources

Aveni, Anthony. Skywatchers of Ancient Mexico (book)

~ A l i c e !

It’s time for the 15th seasonal sunset watch!!

Also, no, the world isn’t ending, the planets aren’t aligning, gravity isn’t shifting. Go donate to your favorite science education or critical thinking organization in solidarity with scientific thinking.

• When: Friday, December 21 at 4:05pm (so come at 3:45pm)
  • Actual sunset is supposed to be at 4:20pm, but at the summer solstice we noticed that the Sun set about 10 minutes earlier than the USNO says it does, so I’ve moved the time of our sunset watch up so we don’t miss it. Last autumn the timing seemed to line up correctly – what will it do this time?
  • The equinox moment is at 3:12am… but we’re watching the sunset not the sunrise because of how the park lines up.
• Where: Solstice Park – all the way up the hill from the tennis courts (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
• Who: Everyone welcome, as usual.

Sunset on September 23, 2011 Image credit: Jason Gift Enevoldsen

Come watch the winter solstice sunset at Solstice Park in West Seattle on Saturday the 22nd. We’ll see if the sunset lines up with the placed marker. I’ll be there even if it is cloudy because sometimes the Sun peeks through just as it begins to set, but if it is driving rain or sleet I’m staying home with some hot tea! This year I’ll be there NO MATTER THE WEATHER: ice, sleet, snow, pouring rain, or even (as unlikely as it might be) sunshine. I want to make sure you have someone to answer your 2012 questions.

If you’re interested – here’s the timing of various celestial events  from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:

Sun and Moon Data for One Day

The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):
Friday 21 December 2012 Pacific Standard Time

SUN
Begin civil twilight 7:19 a.m.
Sunrise 7:55 a.m.
Sun transit 12:08 p.m.
Sunset 4:20 p.m.
End civil twilight 4:57 p.m.

MOON
Moonrise 12:01 p.m. on preceding day
Moonset 1:29 a.m.
Moonrise 12:26 p.m.
Moon transit 7:24 p.m.
Moonset 2:32 a.m. on following day

Phase of the Moon on 21 December: waxing gibbous with 66% of the Moon’s visible disk illuminated.

First quarter Moon on 19 December 2012 at 9:20 p.m. Pacific Standard Time.

This event is my part of the NASA’s Solar System Ambassador program, and thanks to West Seattle Blog for publicizing the last few!

Everyone is welcome, see you there!

~ A l i c e !

Happy Ada Lovelace Day everyone!

Because my birthday was this past weekend, I wanted to tell you about one of the great women of astrophysics: Henrietta Swan Leavitt.

What does this have to do with my birthday? I can hear you asking that. See, my parents are wonderful, thoughtful, creative geeks. And they got me an American Girl doll for my birthday. (YES, my birthday this year. YES, I’m an adult). But then they dressed her up like Henrietta Swan Leavitt. She even has accessories!

(Reply to this post to vote for my parents to create a whole line of women scientist outfits for American Girls dolls! I sure do…)

My American Girl Woman

I was in transports of delight. Yes, my mother sewed those new clothes for her. (The skirt is leftover fabric from my prom dress oh so many years ago.). My father worked on the accessories:

• Light-box
• Magnifying glass (it works)
• Flyspankers (see paragraph 2: http://www.starwrite.org/harvard.html)
• Folio with “glass” plates of the Magellanic Clouds, Henrietta’s scientific paper on Cepheid Variables, and photographs

Henrietta Swan Leavitt

Henrietta Swan Leavitt made it possible for us to measure the size of the Universe.

Yup. read that again. Henrietta Swan Leavitt made it possible for us to measure the size of the Universe.

Ostensibly she was working as a “computer” (what women who did the computational or classification work in astronomy were called in those days) for Dr. Edward Pickering at the Harvard College Observatory.

It was there, rubbing elbows with other famous women of astrophsics like Annie Jump Cannon, as she was classifying the sizes of variable stars in the Magellanic Clouds that she discovered the period-luminosity relationship in Cepheid variable stars.

Variable stars are, as they sound, stars that vary in brightness. What Henrietta discovered, is that for Cepheid variables, the brightness of the star (luminosity) and the period (time between brightest moments) are related. The longer between “blinks” the brighter the star. This means that if you can see a star varying and time between the “blinks” you can figure out how bright that star actually is, not just how bright it looks. (Remember that farther away stars look dimmer, but if you got closer to them they’d look brighter).

By knowing how bright a star truly is, you can accurately measure the distance to that star by how dim it appears to be. Which means you can now measure the distances to things outside our galaxy.

Go read up some more… and let’s investigate the rest of those women computers from Pickering’s lab. Did they all make awesome discoveries? Margaret Harwood, Mollie O’Reilly, Edith Gill,  Evelyn Leland, Florence Cushman, Marion Whyte, Grace Brooks, Arville Walker, Johanna Mackie, Alta Carpenter, Mabel Gill, and Ida Woods.

Want More?

*In case you’re curious, the doll is the newest historical American Girl: Caroline, with her hair pulled back in a bun.

Henrietta Swan Leavitt from the AAS

Cepheid Variable Stars

Links!

~ A l i c e !

It’s time for the 14th seasonal sunset watch!!

• When: Saturday, September 22 at 7:00pm (so come at 6:45pm)
  • Actual sunset is supposed to be at 7:09pm, but at the summer solstice we noticed that the Sun set about 10 minutes earlier than the USNO says it does, so I’ve moved the time of our sunset watch up so we don’t miss it. Last autumn the timing seemed to line up correctly – what will it do this time?
  • The equinox moment is at 7:49am… but we’re watching the sunset not the sunrise.
• Where: Solstice Park – all the way up the hill from the tennis courts (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
• Who: Everyone welcome, as usual.

Sunset on September 23, 2011 Image credit: Jason Gift Enevoldsen

Come watch the autumn equinox sunset at Solstice Park in West Seattle on Saturday the 22nd. We’ll see if the sunset lines up with the placed marker. I’ll be there even if it is cloudy because sometimes the Sun peeks through just as it begins to set, but if it is driving rain or sleet I’m staying home with some hot tea!

If you’re interested – here’s the timing of various celestial events  from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:

Sun and Moon Data for One Day

The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):

Saturday 22 September 2012 Pacific Daylight Time

SUN
Begin civil twilight 6:26 a.m.
Sunrise 6:57 a.m.
Sun transit 1:02 p.m.
Sunset 7:06 p.m.
End civil twilight 7:37 p.m.

MOON
Moonset 10:48 p.m. on preceding day
Moonrise 2:45 p.m.
Moon transit 7:17 p.m.
Moonset 11:52 p.m.
Moonrise 3:31 p.m. on following day

First quarter Moon on 22 September 2012 at 12:41 p.m. Pacific Daylight Time.

This event is my part of the NASA’s Solar System Ambassador program, and thanks to West Seattle Blog for publicizing the last few!

Everyone is welcome, see you there!

~ A l i c e !

I had to do it. I’m collecting memes about Curiosity’s landing on Mars. I’ll do my best to keep up, but I will probably fail soon, due to the viral and meme-y nature of the internet.

A joke made by many.

The Flight Director.

He’s his own meme now too.

http://whatstrending.com/2012/08/meet-mohawk-guy-nasa-mars-curiosity-livestream/

xkcd.
Not really a meme, but worth including.

Curiosity killed the cat.

 http://www.quickmeme.com/meme/3qdanz/

http://www.quickmeme.com/meme/3qd993/

This post is a job for tumblr. Too bad I don’t have a tumblr account.

Funny, too many to post: http://www.quickmeme.com/Unimpressed-Curiosity/?upcoming

Here’s one:

 http://blog.makezine.com/2012/08/05/sometimes-we-live-in-the-future/

From Boing Boing:

Maaaaaars?

MARS!

Marsmarsmarsmarsmarsmarsmarsmars …

Kate Davis via Boing Boing.

You know how I said I was going to give up? Well, now it is time to give it up. I can’t keep up. :) It was fun anyway.

There’s not much I can add to what’s already been said, so I’ll settle for answering a few questions brought up at tonight’s landing watch party and sharing some photos from our party as well as the first shots from Curiosity.

Your Questions, Answered

Is that really nylon rope?

Yes.

I was inspired by Emily Lakdawalla’s post about the “cables” used during the Sky Crane Maneuver to bring a sample to tonight’s party. She managed to get her hands on a piece of the cord that had been used during testing. The look and feel were identical to nylon rope, so I stopped by Home Depot to get 7.5 meters of nylon rope. I brought her photo along and bought the closest thing they had. It was pretty darn close: similar diameter, same color, braided (different braid pattern), nylon rope. You can see mine hanging from the ceiling in some of the party pictures below. This is a close-up of the real rope:

Emily Lakdawalla and Curiosity’s cable

Curiosity was lowered 7.5 meters on three of these cords. But is the cord really nylon like the rope I got at Home Depot? Yes. All the NASA websites say “nylon cable” or “nylon cord.” I can’t tell if they did anything special beyond the style of braiding, but the main material was definitely nylon.

One other difference: my rope was rated to support 194 pounds. NASA’s cords each needed to support at least a third of the rover’s total weight (1 ton), so a single rope needed to support 333 pounds. (Whoops. I’m living in a wishful world of metric.) 1 ton is 2000 lbs, not 1000. So a single rope would need to support 660ish pounds. Then I realized I don’t know if that 1 ton weight is on Mars or on Earth. Which matters quite a bit.

Curiosity weighs 2000 lbs on Earth, 750 lbs on Mars. So each cord will hold about 250 lbs. Still needs to be stronger than my rope.

How does the plutonium power the rover?

This rover is powered not by solar panels but by a “Radioisotope Power System.” Basically, nuclear power.

This doesn’t mean there’s a nuclear generator onboard. Rather there’s a small block of plutonium (specifically plutonium-238), which is slowly decaying into uranium-234 and eventually into lead. (Wait, don’t turn away just yet, I’ll explain!) As the plutonium decays it releases a good amount of heat because of that famous equation E=mc². (I’m not going to give the lecture on radiation, nuclear power, and E=mc² today, rather I’m going to skip straight to the heat part.)

How does the heat power the rover? There are these awesome devices called thermocouples which, when heated, create electricity. It’s the same effect that makes a plug-in cooler work, but for the cooler you’re doing the process backwards. You add electricity, and it makes the thermocouple cold on one side and hot on the other. Onboard Curiosity, the plutonium is warming up one side of the thermocouple, which makes electricity flow through the circuit.

That electricity is captured in batteries, and Curiosity runs off the batteries.

Curiosity’s First Photos

The first photos returned were simple low-resolution images from the hazard-avoidance cameras near the wheels of the rover. By low-resolution I mean LOW–way less than a megapixel, a mere 64 pixels by 64 pixels. And the sheer number of people trying to download that image brought NASA’s servers to their knees. (The livestream of the landing didn’t bring the servers down, just that first image …)

First photo-can you tell there’s a wheel there?

Curiosity Phones Home

(You put your right wheel in, you put your right wheel out, you put your right wheel in and you shake it all about …)

Here are the “high resolution” photos we got a few minutes later (256px square)

Our Party

The Enevoldsen Interpretation Team

My dad, Keith, did way more for this event than I did. Recall all those Lego rover Rocker-Bogie mechanisms he made? Well, he kept going. Thanks, Dad!

Also, my brother, Nils, and husband, Jason, were on hand answering all kinds of Mars and Curiosity questions, and shouting out facts I was forgetting to share. Thanks to you too.

More of the party

See my nylon cord hanging in the back of this picture?

Want More?

Links for more from Curiosity

Here’s where the newest photos will be posted, albeit without explanations.

Curiosity’s home page

How Do We Talk to Mars? I was reminded today of an old post of mine about communication with Mars. I was reminded by the BAJILLION hits on it, I’d completely forgotten. It’s still accurate, so check it out.

News coverage of our party!

West Seattle Blog–Tracy came to join us shortly after an evening of fielding UFO calls based on a number of sky lanterns released in south West Seattle. Always a great supporter of all my events, thanks so much!

West Seattle Herald joined us and got some great shots! Again, thanks for the coverage of this awesome and inspiring moment in engineering history.

Seattle Astronomy‘s Greg Scheiderer was also there, and got some great coverage.

~ A l i c e !