THE DAY OF NO SHADOWS

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

We pass an interesting milestone today here on Guam that you won’t read about anywhere else but here. To start our little discussion, I’m going to perform a magnificent feat of magic. Here’s what I want you to do. Point to the position of the Sun in the sky at noon. Go ahead, point. Now, let me press my hand to my forehead and try to visualize all of you. Let me see . . . . I have it! You’re pointing straight up, aren’t you?

Wow! I’m good. But the interesting thing is, you are wrong. In most places on Earth, the Sun is NEVER straight overhead. In the northern hemisphere, in places like Japan and Europe and the entire mainland US, the Sun is ALWAYS in the southern half of the sky. The Sun is never straight overhead in Australia either or South Africa or New Zealand. It’s always in the northern half of the sky because the Earth is tilted as it spins.

This tilt causes the seasons. When the northern hemisphere is tilted toward the Sun, the Sun is higher in the sky and more direct sunlight falls on the Earth. The northern hemisphere has summer. When the northern hemisphere is tilted away from the Sun, the Sun is much closer to the southern horizon and the Earth cools off. The northern hemisphere has winter.

In the area between the Tropics of Cancer and Capricorn (23ºN to 23ºS), the Sun is always high in the sky and the land is always warm; there are no seasons. In the tropics, the Sun is straight overhead for 2 days a year. The Sun is straight overhead at the equator on 20 March and 20 September, the spring and fall equinoxes. The Sun is straight overhead at 23ºN the Tropic of Cancer, on 20 June, the first day of summer in the northern hemisphere. The Sun is straight overhead at 23ºS the Tropic of Capricorn on 20 December, the first day of summer in the southern hemisphere.

So why am I telling you this? Because today, 26 April is one of the two days every year when the Sun is straight overhead at noontime here on Guam. I call these two days, The Day of No Shadows because when the Sun is straight overhead (and there are no clouds to block its light), there are no shadows at noon and the world looks curiously flat. It’s a subtle effect, but quite noticeable when you know to look for it.

Get an accurate time check for your watch (www.time.gov is the place to go) and go outside at 12:19 p.m. Look at a post or a pole and if it isn’t cloudy, you’ll see that the post or pole casts NO shadow at 12:19 p.m. today.

Starting tomorrow, the Sun will be in the northern half of the sky at noon and it will stay there for four months. This makes sundial construction a little strange here because you have to have the hours marked on both sides of the upright part (the gnomon).

Do something a little different at lunchtime today and celebrate Guam’s uniqueness by observing the Day of No Shadows. Have fun!

IN YOUR HANDS

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

One of the wonders of nature is what’s at the end of your arm. The human hand is an amazing machine that’s capable of all sorts of astounding feats. It can pick up, clench and caress. Although you certainly take your hands for granted, just imagine what life would be without them.

Robots need hands too, and building them has been a real challenge. Now, researchers at Cornell University and iRobot (the makers of the absolutely awesome Roomba vacuum cleaner) have gotten together and made a robotic hand. Ah, you’re thinking, what’s at the end of my arm but made of metal, right? Well, not exactly. They made it out of coffee and a party balloon. Say whut??

They call it a universal gripper and not a hand, since it conforms to the object it’s grabbing rather than being designed for particular objects, said Hod Lipson, Cornell associate professor of mechanical engineering and computer science. He worked with Chris Jones at iRobot Corp.

"This is one of the closest things we’ve ever done that could be on the market tomorrow," Lipson said. The gripper could be used to dismantle explosive devises or to move potentially dangerous objects. It could also be used on robotic arms in factories and perhaps most importantly, on prosthetic limbs.

Here’s how it works: An everyday party balloon is filled with ground coffee and attached to a robotic arm. The coffee-filled balloon presses down and deforms around the desired object, and then a vacuum sucks the air out of the balloon, solidifying its grip. When the vacuum is released, the balloon becomes soft again, and the gripper lets go.

Coffee is a particulate material which means it’s made of a lot of individually solid particles. Particulate materials have what’s called a jamming transition. When the particles aren’t packed tightly together, they move around each other like a liquid, but when they’re tightly packed they become solid and can no longer slide past each other. You’ve seen this yourself if you drink vacuum-packed coffee which is hard as a brick until the package is unsealed.

"The ground coffee grains are like lots of small gears," Lipson said. "When they aren’t pressed together they can roll over each other and flow. When they are pressed together just a little bit, the teeth interlock, and they become solid. What’s particularly neat with the gripper is that here we have a case where a new concept in basic science provided a fresh perspective in a very different area — robotics — and then opened the door to applications none of us had originally thought about.”

As for the right particulate material, anything that can jam will do in principle, and early prototypes involved rice, couscous and even ground- up tires. They settled on coffee because it’s light but also jams well. Sand did better on jamming but was prohibitively heavy. What sets the jamming-based gripper apart is its good performance with almost any object, including a raw egg or a coin — both notoriously difficult for traditional robotic grippers.

Basic principles, new science. Let’s all give these researchers a big hand!

Graduate student John Amend, left, and associate professor Hod Lipson with the universal robotic gripper. (Credit: Robert Barker/University Photography)

News from your Planetarium

By Pam Eastlick

Greetings Everyone,

Well, looking out my library window, I’m not optimistic about seeing the sky tonight and that’s a real shame because there will be a bright pass of the International Space Station just after sunset. But I’ve lived here long enough to know that it could be totally clear by sunset, so I’m passing on the information about how to see it.

We’re also going to try to see it after public shows tonight. Please join us for "The Magic Half Hour" in the Planetarium and then (hopfully) ISS watching in the BIG Planetarium . . . outside!

Pam

There will be a bright pass of the International Space Station TONIGHT, the 16th of April. To see it, watch the Sun disappear from your location and at 7:00 p.m. go outside and face that way. The Sun is setting about 10 degrees north of due west now and you need to measure eight fist-widths along the horizon to the left. You’ll be facing south-southwest, and at

7:05 p.m. you’ll see a very bright ‘star’ appear above the southwestern horizon and begin to climb upwards. At 7:06:20 p.m. the ISS will pass very close to the second brightest star, Canopus.

The ISS will continue to arc higher in the southern sky as it passes toward the east and at 7:08 p.m. it will be above both the waxing Moon and Saturn. It will disappear above the northeastern horizon at 7:10 p.m. and will shine at an amazing -3.5 which is almost as bright as Venus gets. I know a lot of you enjoy waving at the astronauts so get an accurate time check for your watch and enjoy the pass tonight!

IT’S FULL OF STARS!

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond. Visit our website at www.thedeepradioshow.com

Greetings everyone! I’m about to let you in on one of the world’s best kept secrets. Here on Guam, in April and May there’s a half-hour period each evening when you can see something amazing. You don’t have to use any of that precious gas, and you don’t have to pay money to see it. All you have to do is go into your back yard and look up.

If you do and there aren’t too many clouds and streetlights you’ll be able to see eight of the ten brightest stars, fifteen of the twenty brightest stars, the largest and smallest constellations and the three most famous constellations ALL AT THE SAME TIME! This is possible only in the equatorial tropics and it’s probably the best kept sky-watching secret in the world. I call it The Magic Half Hour. This week The Magic Half Hour occurs between 9:30 and 10:00 p.m. Next week, it will occur between 9:00 and 9:30 p.m.

So . . . . how do I find all this starry wonder? Well, the first thing you need to do is watch a beautiful tropical sunset from your sky watching location. Tough assignment, huh? Watching the Sun disappear will tell you where west is.

Then go outside tonight around 9:45 p.m. and face where the Sun disappeared. If you have a clear view to the west, you’ll see a large connect-the-dots picture close to the ground. Many of you will recognize Orion the Hunter, the sky’s most famous constellation. Orion the Hunter is a rectangle of bright stars with three bright stars in a diagonal line in the middle of the rectangle. At this time of year, everyone can see him because he lies above Earth’s equator. That’s why he’s the most famous constellation.

Five of the eight bright stars are close to Orion and if you turn completely around and face east, you’ll see a long triangle of bright stars higher in the sky. The left star is Arcturus, the fourth brightest star and the top star of the two stars to the right isn’t a star. That’s the planet Saturn.

Then turn ninety degrees to your right and face south. See that bright kite-shaped group of four stars? That’s another one of those famous constellations; Crux the Southern Cross and you bet you can see the Southern Cross from Guam. Those two bright stars to the left of the Southern Cross are the remaining stars of the eight brightest stars you can see tonight.

So . . . did I go too fast? Why didn’t I talk about the Big Dipper? That’s the most famous constellation, right? Want to know how to find more bright stars? Have I got a deal for you!

It’s public show week in the Planetarium and our show is “The Magic Half Hour.” In it, we teach you exactly how to find all those bright stars and constellations. “The Magic Half Hour” will be presented this Thursday, Friday and Saturday, 14, 15 and 16 April 2011 at 6:30 p.m. each night.

At 7:00 p.m. we’ll have “Quality Time with the Star Lady” where I attempt to answer your questions about the sky and all things space-related. But what we’re really doing is stalling for time until it gets dark enough that we can go outside and find all this stuff in the BIG Planetarium!

The UOG Planetarium is located on the second floor of the Science Building on the main UOG campus. The doors open at 6:00 p.m. and here’s the really good part: Planetarium shows are FREE!!!!! Join us this weekend and learn all about your personal sky! See you there!

News from your Planetarium

By Pam Eastlick

Greetings Everyone!

Welcome to the best stargazing skies in the world and I say that without fear of contradiction because on Guam in April and May, there’s a half-hour period each evening when you can see eight of the ten brightest stars, fifteen of the 20 brightest stars, the three most famous constellations and the largest and smallest constellations ALL AT THE SAME TIME! This is only possible in the equatorial tropics.

I’ve also been spending some time under the early morning sky. Your eyes are already dark-adapted in the early morning and I’ve been catching an astounding view of the central Milky Way from my very own front yard. But our early morning skies are only beginning to strut their stuff. Next month in early May, they will host a four-planet conjunction!! Our skies are amazing any time though. Enjoy them this week!

Pam

APRIL PUBLIC SHOWS

‘The Magic Half Hour’

‘Quality Time with the Star Lady’

14, 15 and 16 April 2011

Since April and May host the magic half hour when you can see all the wonder described earlier in the newsletter, what better show to feature in April than “The Magic Half Hour” that shows you how to find it all in your personal sky!

Join us at 6:30 p.m. on Thursday, Friday or Saturday when you’ll take a guided tour of Sirius, Canopus, Alpha Centauri and all the rest of the bright stars and then learn about Orion the Hunter, Ursa Major the Great Bear and Crux the Southern Cross. (And yes indeedy, you can see the Southern Cross from Guam and we’ll show you how to find it). We’ll also discover The Great Ship Argo Navis and Hydra the Sea Serpent.

Then at 7:00 p.m. it’s “Quality Time with the Star Lady” when I attempt to answer your questions about the sky, constellations, stars and other

space- related topics. But what we’re really doing is stalling for time until it gets dark. Then we’ll go out into the parking lot and find as much as of the stellar wonder as the time and clouds allow us to. Don’t miss it. It’s a skywatching extravaganza!

The doors open at 6:00 p.m. and Planetarium shows are always FREE!!