Archive for April, 2010

May-June 2010 Starmap

Time flies, and the sky slowly changes. Can you believe it’s May and time for the Summer Triangle already? Welp, it is! Check out the starmap and all these wonderful things to look at. For more – go to the Abrams Planetarium’s Night Sky Notes!

Notable Sky Objects

SATURN

Saturn is beautiful in the southern sky this month – in Virgo’s head. It’ll be one of the two brightest “stars” you can see in the south/southwest. Since Saturn is still mostly edge-on to us I’d recommend a small telescope to pick out the rings, whereas normally you can see them with steadied binoculars.

MARS

Mars continues to grace our skies – shining pinkly in the West after sunset and sticking around until midnight (early May) or only 9pm (late June).

JUPITER

Jupiter rises around 2 or 3 in the morning – you can find it almost due East.

MERCURY/VENUS

Mercury is pretty close to the Sun’s position, but you might be able to catch it  at the end of May just before sunrise. Venus you’ll have to try for just after sunset, because it sets very soon after the Sun does.

EVENTS

June 14 – Earliest sunrise of the year.
June 21 – Summer Solstice.
June 27 – Latest sunset of the year.

New Constellations

SCORPIUS – The Scorpion

SCIENCE: Antares (alpha scorpii) red supergiant of variable brightness with a close blue-white companion orbiting every 900 years. Means “Rival of Mars” (anti-Ares) or “Like Mars”
MYTH: To the Chinese it was a dragon; in the South Pacific, it was Maui’s fishhook used to pull up islands from the ocean floor.

The Summer Triangle (well, we have most of it anyway):

Cygnus(the Swan) and Lyra (the Lyre/Harp) reappear, and the bright star from Aquila (Altair). The summer triangle (as you can tell by the name) will be directly overhead come summer, but now it’s low in the East, a harbinger of brighter days to come.

CYGNUS – The Swan

SCIENCE: Albireo – Cygnus’ head is the prettiest double star in the sky. Look through a telescope and it separates into a glowing gold star, and a tiny blue point. This is a good thing to suggest for people with telescopes at home.

Albireo by Jared Smith

MYTH: Do you like gory details? When his brother Phaethon was killed by Zeus and scattered all over the Earth, Cygnus picked up all the pieces. The gods laughed, calling him a “bobbing duck,” picking up all those pieces. Then they started to realize that maybe he was doing a good deed, so they put him in the sky as a “noble” bobbing duck – a swan.

LYRA – The Lyre

SCIENCE: M57, the Ring Nebula is between the bottom two stars in the constellation. It’s pretty hard to pick out, even with a small telescope, but it is a good target for larger scopes, and Hubble has a beautiful image of it.

M57 Ring Nebula Source: Hubblesite.org

DELPHINUS – The Dolphin

This tiny constellation is as cute as a bug’s ear … or a dolphin’s. Probably one of the easiest constellations to spot – Delphinus is isolated in a dark part of the sky near Aquila.
MYTH: The four stars that make Delphinus’ head are also called “Job’s Coffin.” In the United States you don’t often think of Christianity as the underrepresented religion, but in our sky it is: the sky is dominated by the Greek names and stories.

“Tiny” Guys

Going for the Gold? Here’re this month’s itty-bittys.
LYRA – The Lyre
CORVUS – The Crow
CRATER – The Cup
COMA BERENICES – Berenice’s Hair
LYNX – The Lynx
SEXTANS – The Sextant
HYDRA – The Sea Serpent (Big and dim)
LACERTA – The Lizard
LEO MINOR – The Small Lion (Between the Big Dipper and Leo)
VULPECULA – The Fox
SAGGITA – The Arrow
SCUTUM – The Shield
LIBRA – The Scales
CAMELOPARDALIS– The Giraffe

Returning Constellations

BOÖTES – The Herdsman
HERCULES – Hercules
CORONA BOREALIS – The Northern Crown
VIRGO – The Virgin (or “Princess”)
LEO – The Lion
CANCER – The Crab
GEMINI – The Twins
CEPHEUS – King Cepheus
DRACO – The Dragon
URSA MAJOR – The Great Bear
URSA MINOR – The Little Bear
CASSIOPEIA – The Queen

Where’d I Get My Info?

My memory, and Zeta Strickland

~ A l i c e !

One of the small, unassuming—and much cooler than you might expect—exhibits at Pacific Science Center is the Particle Aquarium, also known as a cloud chamber or cosmic ray aquarium.

In Short

The particle aquarium creates a supersaturated environment of alcohol vapor. Charged particles (from space as cosmic rays or from radioactive decay closer at hand) pass through this supersaturated field. They leave behind a trail of ions, and those ions are nucleation sites, places where the alcohol vapor can condense into liquid droplets, which makes a trail of tiny droplets of alcohol. You see those trails, so you’re seeing the path of a cosmic ray from space.

As many cosmic rays as you see in the chamber, there are more than that there, and just that many are going through your body too at this very moment. You can also identify characteristics of the particle by examining the shape of the path.

How it Works

Look closely.

At the top is a place where alcohol is dripped into a small tray that runs around the edge. This is where the alcohol is heated until it evaporates, filling the entire chamber with alcohol vapor. At the bottom of the chamber is a chilled plate. As the vapor falls towards the plate it cools, creating a supersaturated layer of vapor near the bottom of the chamber. This layer is primed and ready to condense, it just needs a little push.

Any kind of push will create condensation in the supersaturated layer. As a charged particle passes through air it leaves a trail of ions in its wake. This is not to say ions are falling off the charged particle—no, it is interacting with the molecules in the air, turning them into ions.

Those ions cause the supersaturated alcohol vapor to condense, which shows the trail of the charged particle. The droplets fall to the cooled plate, and the track disappears.

Charged Particles and Ions

Remember back in chemistry when you learned that an atom has protons and neutrons in the nucleus, and is surrounded by a cloud of electrons? You also learned the protons (positive charge) and electrons (negative charge) tend to be in balance with each other, giving you a neutral atom. Depending on your teacher she might have called this a “happy atom.” Well, knock one of those electrons away—because it’s way more complicated to knock off a proton, we call that fission—and you create a positive ion, or what your teacher might have called an “unhappy atom.” You can do the opposite too—add an electron—and you have a negative ion.

Well, charged particles are, by their very definition, charged. Positive charges and negative charges attract, negative and negative repel, and positive and positive repel. So, if you get a charged particle near a neutral air molecule you could very well affect the outer electrons for that molecule. (And yes, I switched from using atoms to molecules – they work the same way in this case)

Cosmic Rays and Radioactive Decay

There are all kinds of cosmic rays in space (mostly from the Sun) and a good number of those make it down through our atmosphere to us. Not nearly all of them though, our atmosphere protects us. Here are three major types of rays:

• Alpha radiation is Helium nucleii (Heliums without electrons)—they have a positive charge, and are fairly heavy as particles go.
• Beta radiation is either electrons or positrons. When they’re electrons they have a negative charge, when positrons they’ll have a positive charge. These are fairly lightweight.
• Gamma radiation is photons. They’re charge-less and very lightweight.

Watch for

• Thickness: heavier particles can make thicker lines
• Speed: faster particles travel straighter
• Deflection: a ray’s interaction with other particles, electrons, etc will cause deflection
• Simultaneous events: probably from the same source
• Cascade events: one ray/particle interacts with something, causing several rays/particles to be released making their own tracks.
• Wandering: often caused by a low-energy ray making many interactions
• Curvature: in the presence of a magnetic field, positively charged particles will curve one direction and negatively charged particles will curve the opposite way.

Experiments to Think About

Both of these mean acquiring items which are generally not that safe to carry around unprotected, and sometimes require special licenses to have in your possession.

• Introduce a strong magnetic field. The path of a charged particle changes in the presence of a magnetic field.
• Introduce a radioactive source. Radioactive sources create charged particles.

Vocabulary

Supersaturated—when mixing sugar in your tea, you can only dissolve so much. If you heat up your tea you can dissolve more. If you then let your tea cool off, under ideal conditions, the sugar stays dissolved, even though you couldn’t have dissolved that much sugar in cold tea. This is a supersaturated solution – it’s more saturated than you could make it normally. This is why you should either add sugar to your iced tea before you cool it – or you have to add sugar syrup.

Nucleation site—if you then drop a sugar crystal or some such into the cold, supersaturated tea a the sugar will start to come out of solution and grow more sugar crystals on that first one. The first crystal (which can sometimes just be a rough spot, a spoon, a string, or a piece of sand) is the nucleation site. It acts as a nucleus for the new crystals.

Ion—an atom with too many or too few electrons.

Reservations

I need to do more research, there are two major problems with this article. First – I use the words particle and ray almost interchangeably, I should sort that out. Second – I would like to clarify how to identify types of radiation, and the likelihood the rays you’re seeing are from space versus from radioactive elements in the Earth. I’ll keep working on it, but this should definitely get you started on figuring out how awesome the particle aquarium is. Oh, and I want to stick in some pictures.

Want More?

Andy Foland’s Cloud Chamber
Cloud Chambers
More Cloud Chambers
A Great Lesson Plan (College Level)
A Place to Practice Identifing Tracks

~ A l i c e !

Eyjafjallajökull's ash plume in April 2010 from NASA's Earth Observatory

The Eruptions

Eyjafjallajökull has been active in the last few days. Dr. Erik Klemetti of Eruptions blog has a great write up. Go listen to him. Also, Jorge Santos has the best picture of the ash.

Most recently, on 4/14/2010 (or 14-4-2010 if you’re not in the US):

After a few days of quiet in Eyjafjallajökull volcano, a new and much more forceful eruption has begun west of Fimmvörðuháls, under the ice-cap.

The eruption is below the highest peak of Eyjafjallajökull, at the southern rim of the caldera.

A plume rises at least 8 km into the air. No lava is seen yet but melt-water flows both north and south of the mountain.

-Iceland Meteorologic Office

At 2300 on 13 April, a seismic swarm was detected below the central part of Eyjafjöll, W of the previous eruption fissures. About an hour later, the onset of seismic tremor heralded an eruption from a new vent on the S rim of the central caldera, capped by Eyjafjallajökull glacier. The eruption was visually confirmed early in the morning on 14 April; an eruption plume rose at least 8 km above the glacier. Meltwater flowed to the N and S. News outlets reported that a circular ice-free area about 200 m in diameter was seen near the summit. Scientists conducting an overflight saw a new 2-km-long, N-S-trending fissure, and ashfall to the E. About 700 people were ordered to evacuate the area, and certain flights were banned from flying N and E of the eruption area. Flooding increased throughout the day, causing road closures and some structural damage.

-Institute of Earth Sciences

The Volcano

Eyjafjöll is also known as Eyjafjallajökull. It’s a strato volcano – so more of a pointy volcano (like Mount Vesuvius), less of a flat volcano (like Hawai’i). Eruptions from strato volcanoes are often more powerful and spread more ash and less lava. Near Seattle the Cascades have many strato volcanoes: Mount Rainier, Mount Saint Helens, Crater Lake, Shasta, etc.

Good places for more information?

The volcano itself (from the Global Volcanism Program).

The eruption on 4/14/2010 (from the Iceland Meteorological Service)

News from the Iceland Meteorological Service

USGS Worldwide Volcanic Activity Report

NASA’s Earth Observatory Photographs from Space

~ A l i c e !

First off Astronaut Greg Johnson will be at this week’s Science with a Twist on Thursday April 15th at Pacific Science Center. The event is also on Facebook. I’ll be there too, holding a brief discussion about false color, and Toni Meyers, director of Hubble 3D will be speaking about the film.

“Science with a Twist will celebrate Hubble 3D. Toni and Greg will circulate during the event and introduce the film and answer questions after the film. Pacific Science Center’s resident NASA Solar System Ambassador, Alice Enevoldsen, will  also lead you through an explanation of astronomical images: What do you see vs. What’s really there? Tickets for staff are only $17 (21 +, ID required)”

Toni Myers is the director and producer of Hubble 3D and one of the few women directors in the history of IMAX filmmaking. Toni has worked on IMAX documentaries since 1971. She has worked on every IMAX space film and has worked directly with over 120 astronauts and cosmonauts in the making of the IMAX space films. She has an extensive background in a variety of films in addition to  IMAX filmmaking .  In addition to documentary projects she has a background in the music world having worked on music projects for the Beatles’ company, Apple; and individual features and videos for John Lennon and Yoko Ono. The IMAX documentaries that Toni has worked on have been among the most successful here at the Science Center including Under the Sea 3D.   For her work on Hubble 3D  the astronauts of the STS-125 crew presented her with the Silver Snoopy Award in recognition of her excellence and

achievements in bringing the space experience to IMAX audiences around the world.

Greg Johnson graduated from West Seattle High School and from the UW  with a degree in aerospace engineering.  He received his Naval Aviator wings in December 1978.  He served as a senior research officer in Office of Naval Research. He has logged over 9500 flying hours in 50 aircraft and has over 500 carrier landings. In 1990, he was accepted as an aerospace engineer and research pilot at NASA . He joined the astronaut program in 1998. He was the pilot the final Space Shuttle mission to the Hubble Space Telescope. On this mission he logged almost 13-days in space—–traveling 5,276,000 miles in 197 Earth orbits at 17,500 miles per hour. And he was an IMAX cinematographer on the mission.

Next, April 24th will be Astronomy Day at Pacific Science Center. Here’s a copy of that e-mail:

Calling all astronomy enthusiasts!

Celebrate the 20^th anniversary of the launch of the Hubble Space Telescope at Pacific Science Center on April 24th.

What: Pacific Science Center presents Astronomy Day

When: Saturday, April 24^th 10am-6pm

Where: Pacific Science Center

Astronomy Day this year will be in style at Pacific Science Center! With planetarium shows, hands-on exhibits in Facing Mars, facilitated space-themed activities with our onsite Science Interpretation staff, crafts, and the eagerly-anticipated IMAX film Hubble 3D this day of science just won’t end.

IMAX FILMS

Hubble 3D

Showing April 24^th at 10:30am & 11:45am

The perfect way to celebrate the 20^th Anniversary of the launch of the Hubble Space Telescope is to take in a screening of this new IMAX film which is gaining rave reviews! Today’s Seattle Times review calls Hubble 3D an “extraordinary spectacle” and an “out of this world documentary.” http://seattletimes.nwsource.com/html/movies/2011381515_mr19hubble.html

Roving Mars

Showing April 24^th at 11:30am, 1:30pm, 3:30pm and 5:30pm

Go behind the scenes with NASA scientists and engineers as they worked to design Mars Rovers, Spirit and Opportunity, to travel millions of miles to Mars and report back!

FEATURED EXHIBIT

Facing Mars

Open 10am-6pm

Here’s your chance to experience the sensations, emotions and conditions of a real trip to Mars without ever leaving Earth! Build your own simple rocket, take a “Mars Walk,” see firsthand what microgravity does to the human body and so much more!

Last, you should go look at Carnival of Space #149!

Okay, enough advertising. I’ll tell you more science-y stuff next week.

~ A l i c e !

The fabulous and illustrious duo Beth and James requested that I educate you all further on the relationship between the Chilean Quake and the rotation of the Earth. A worthy topic.

In Short

The big earthquake in Chile shifted enough of the mass of the Earth far enough that (like a figure skater bringing her arms in toward his body) the Earth actually sped up slightly – shortening our day by 1.26 microseconds. Maybe – the number will be refined further.

Quote

JPL research scientist Richard Gross computed how Earth’s rotation should have changed as a result of the Feb. 27 quake. Using a complex model, he and fellow scientists came up with a preliminary calculation that the quake should have shortened the length of an Earth day by about 1.26 microseconds (a microsecond is one millionth of a second).

Perhaps more impressive is how much the quake shifted Earth’s axis. Gross calculates the quake should have moved Earth’s figure axis (the axis about which Earth’s mass is balanced) by 2.7 milliarcseconds (about 8 centimeters, or 3 inches). Earth’s figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet).

-JPL Media

In Detail

Overwhelmed? I’ve highlighted the pieces you should pull out of that.

Conservation of Angular Momentum

You cannot create energy or matter out of nothing. These laws are called “conservation of matter” and “conservation of energy.” We’ve got one for spin (angular momentum) too. If you’re spinning you either keep spinning (at the same speed) or you pass off some of that momentum to another object. This causes the oft-referenced effect of the figure skater’s pirouette. She begins to spin with her arms out, gets up some speed, and then pulls her arms and legs in tight. She spins significantly faster in this configuration. Later she puts her arms out again and slows down.

You can do this at home. Grab two cans of food and a spinning office chair. If you do not also find yourself at least fifteen by fifteen feet square of clear space, I take not responsibility for your bruised knuckles (you WILL knock into something if you don’t have plenty of room around, so don’t hurt yourself). Get a friend to start you spinning, with the cans held at arms length in your hands. As soon as you’re going, pull the cans in to your body. Try it the other way – starting with your arms in too.

This is conservation of angular momentum.

Figure Axis

Why were we talking about that? Because of the figure axis. You know the Earth is round, and you also know the Earth is not a perfect sphere because of that hill you had to bike up to get to work today. The Earth rotates on its axis, once a day, and that axis is pointed at the North star.

Now, imagine your washing machine – it spins too. Where is that axis? Yup, right down the middle. The figure axis is different though – it’s the axis around which the mass is all balanced. In a normal situation for your washing machine, these two axes are about the same. Now imagine it gets off balance – all your clothes end up on one side of the drum.

First, where is the spin axis? Yes! Same exact place – right down the middle (sorta, you hope). The mass (your soggy clothes) have changed places though, and they’re all on one side. Imagine a line that intersects the middle of the clothes pile. It’s off to one side, and in fact, as the washing machine spins, the figure axis is rotating around the spin axis with the clothes.

Re-balance your load of laundry so it doesn’t make your washing machine walk and let’s talk about the Earth.

The Earth’s figure axis (balance of mass) is very close to its spin axis, but they aren’t the same. If you move one of the Earth’s plates a lot – it’s like moving the towel in the laundry around, you’re messing with the balance of the mass. In the case of the Chilean earthquake we have one plate subducting under another, which means some mass moving closer to the center of the Earth. It’s not moving far, it’s not getting that much closer to the Earth, but if you’re doing minute calculations it is definitely enough to have that conservation of angular momentum effect (spin a little faster as mass moves in) due to the shifting of the mass of the Earth.

Calendar Change

A student came up and asked today if that meant the atomic clocks needed to change. Well, no, but the atomic clocks are pretty much just counting time passing anyway, in oscillations specific atoms. The question you want to ask is, are the “atomic calendars” going to change?

First off, I must point out I don’t know if there are calendars kept to the level of accuracy that is implied in the term “atomic calendar.” Perhaps these folks?

Second, no, not yet. Richard Gross’s calculations are preliminary. Once they are solidified, the next leap second will take care of it. Does that mean a leap second isn’t actually exactly a second?

Want More?

The JPL Release

Microseconds – a measure of time

Milliarcseconds – a measure of angle (like a degree is a measure of angle)

International Earth Rotation and Reference Systems Service

I’m embarrassed to say, but I got the idea for the  washing machine analogy off Yahoo Answers. I was just going to use the figure skater till I read the concept there. I’m also going to have to talk about the ways the Earth moves sometime.

~ A l i c e !