A good Science Fair project involves a journey of discovery, driven by curiosity.  My First Weather Kit does just that.  Learn all about extreme weather with this complete weather station. Explore why we have hurricanes and typhoons, why global warming makes ocean levels rise and more as you become a weather expert! ($19.95)

 Another fun activity for young science enthusiasts is our Volcano Making Kit. Make a volcano with the plaster and mould provided, paint in the lava flow and landscape, then create your eruption by mixing baking soda and vinegar. ($9.95)

For older students, curiosity shines through our Solar Energy Laboratory. Build a solar energy laboratory and conduct more than 25 energy conservation experiments.  Use a solar collector, solar heater and other tools to collect and measure energy. ($9.95)

If your child is a fan of MythBusters, the kits below should definitely peak their interest…

Have a blast working with the Power of Air Pressure Kit and answer questions like, ‘Will your stomach really explode if you don’t belch?’ and ‘Can air alone support a train?’ while witnessing the power of air pressure in action by building a marshmallow launcher. ($19.95)

Take the lead through an exploration of aeronautics with the Forces of Flight Kit. We are surrounded by flying object every day, but can you explain the science behind it.  Learn and experiment to find the answers to questions like, ‘Can a plane really steer itself?’ ‘What would happen if an astronaut didn’t wear a space suit?’ Experiments include flying a model helicopter and launching a rocket. ($19.95)

With the Weird World of Water Kit, you will experiment to learn just how strong a whirlpool is, discover whether it’s possible to walk on water and test the limits of water’s power by building and launching a water-powered rocket! ($19.95)

Come down and visit Planet Fun for an array of these and other activities. We look forward to seeing you and good luck with those science fair projects!

The most obvious would be the lack of a sky glow produced by a myriad of outdoor lights. This glow washes out the richness and beauty of the starry sky, except for those few that live far away from light polluted cities.  

The second difference is more subtle. While most of the stars and constellations would appear the same, a few stars would be out of place. One of the most noticeable is Arcturus, fourth brightest star in the night sky. Arcturus, a red giant, is a prominent star on clear spring evenings. It can be found by following the curve made by the handle of the Big Dipper. As you observe it, can you detect a hint of red or orange color?

What makes Arcturus different? It is a galactic invader, a star that was once part of a small galaxy that was ripped apart and absorbed by our Milky Way Galaxy in the distant past.

Our Sun is in motion around the center of our galaxy. Most of the stars around us are in similar orbits, so we all move more or less together, like a large flock of migrating birds. Because of this, stars appear motionless over time spans as short as several thousand years. In contrast, Arcturus has a very different orbit. It is currently plunging down through the galactic plane, moving sideways to the local stellar “traffic stream,” That is why this bright star shifts its position noticeably with time. It takes Arcturus slightly less than 1600 years to move one degree in the sky, twice the apparent width of the full moon.

So, as the weather begins to warm, look off to the east and greet this galactic visitor.

The size or area of a square is the product of its length and width.  If each side is doubled, or increased by a scale factor of 2, the area increases by 2 x 2 = 4. If each side is tripled (a scale factor of 3), the resulting square is 9 times larger. In general, the area increases by the square of the scale factor. While this is easiest to visualize using a square, a picture of any object on the square would scale up or down the same way, so this works with any shape.

Since area increases as the square of the scale factor, if I wish to double it, I need to use a scale factor whose square is 2. This is √2 = 1.414. So, I set the copier to 141% and doubled the size of the chart on my first try, with no wasted paper.

How about a cube? If each side of a cube is doubled, the result is a cube 8 times as big. In general, the volume of any object changes as the cube of the scale factor.

So, how big is the Sun compared to Earth? It depends on what is meant. The Sun has a diameter 109 times larger than Earth.

So if we mean “How many Earths put side to side would be as wide as the Sun?” the answer is 109. However, if we mean “How many Earths would fit inside the Sun?” we are dealing with volume, so the answer is 109 cubed or about 1,300,000!

This relationship can be explored with all the planets by comparing the “Equatorial Diameter” and the “Volume” in the Clark Planetarium Solar System Fact Sheet. “Volume” is really telling us how many Earths would fit inside the larger planets or what fraction of Earth would fit inside the smaller planets. (Note: a planet’s volume is the cube of its average diameter, not the equatorial diameter given in the fact sheet).

Scale away!

Placing flags on the moon is something NASA thought a lot about when they were planning the Apollo missions in the mid 1960’s. NASA even went so far as to create a “Committee on Symbolic Activities for the First Lunar Landing” to figure out how best to have the astronauts carry out their PR duties on the moon without jeopardizing either their safety or their extensive science to-do list.

The 1967 United Nations “Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies,” (which the U.S. signed) included this prohibition: “Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of occupation, or by any other means.”

So why then plant a flag on the moon? For the symbolism, of course! Just as people feel the need to stick flags on the summits of mountain peaks, NASA wanted to put a US flag on the moon as a way of saying, “Look everyone! Americans are on the moon!”

Having astronauts plant the flag once on they’re on the moon was easier said than done. The Lunar Module (LM) was already crowded with equipment and supplies and there was no room to spare in the LM for the flag. Weight was a critical issue. The astronaut’s bulky, pressurized space suits meant that they’d have limited range of motion and limited dexterity with their gloves. This meant that the flag had to be simultaneously lightweight, compact, and extremely simple to set up.

NASA engineers, being extremely clever people, figured out a way to package telescoping poles and a folded flag into a small, narrow container and mount it on the ladder the astronauts would use to get out of and back into the LM.

NASA bought the flags that are on the moon for $5.50 each from a commercial flag manufacturer through standard government contracts, and then spent several hundred dollars insulating each flag kit package to protect them from the 2,000 degree temperatures that the packages would experience during landing because they were in the vicinity of the LM’s decent engine’s flaming exhaust.

July 20, 1969! “One small step for (a) man, one giant leap for mankind.” Millions of people around the world (including 14 year-old me) watched as Aldrin and Armstrong detached the flag kit from the ladder, placed the flag on its vertical and horizontal poles, and then… the telescoping mechanism on the horizontal pole stuck. It wouldn’t fully extend, leaving the flag still somewhat scrunched-up. The astronauts fiddled with it for a minute or two without success and then decided that, hey, it actually looks better this way!

Other Apollo astronauts, seeing this, all agreed that the flag in fact did look better this way, and decided that they, too, would only partially extend their horizontal flag supports and thus create a more “natural” looking flag when it was their turn to plant their flags on the moon – which they all did.

And regarding the “flapping” of the moon flags in certain movies of the Apollo astronauts working on the moon, remember that the moon is completely airless and has 1/6^th the surface gravity of Earth. This means that the slightest bump will set the flag’s fabric into motion and it will continue to “flap” for far longer than you’d expect fabric to if were on Earth.

And if you’re part of the 6% of the population who really believe the moon landings were faked and you want to argue, well, I’m sorry, that’s an invitation to just waste both of our time.

A quick look at “Average Orbital Velocity” in Clark Planetarium’s Solar System Fact Sheet will reveal that the farther a planet is from the Sun, the slower it moves. In contrast, stars and gas in the outer regions of galaxies all have roughly the same speed regardless of their distance from the center. How do astronomers measure their speed? Using the Doppler Effect. Below is an example from a nearby galaxy known as M33. The image on the right is a radio telescope image showing the distribution of hydrogen throughout the galaxy (hydrogen atoms give off radio waves with a wavelength of 21 centimeters). Colors in the image show the Doppler shift of the radio waves. Blue shows hydrogen that is moving toward us. Red shows hydrogen that is moving away.

Right: M33 Galaxy (credit: NOAO/AURA/NSF/T.A.Rector). Left: M33 Galaxy showing Doppler shift (credit NRAO/AUI)

Since Doppler measurements reveal that stars and gas in the outer regions of galaxies all have similar speeds, this implies that mass in a galaxy must increase with increasing distance. But visible matter in most galaxies appears to decrease with increasing distance from the center. So, unless our understanding of the basic laws of physics needs a tweak (as has been proposed by some) most of the mass in galaxies cannot be seen, hence the name dark matter.

A number of possibilities have been suggested for this unseen mass, from dim stars, brown dwarfs and black holes to exotic and not so exotic sub-atomic particles. Recent searches seem to favor sub-atomic particles. However, one of the exciting things about astronomy research into the unknown is that an unexpected discovery or a better observation can revise current thinking.

Hubble composite showing ring of dark matter in the galaxy cluster C1 0024+17

One of the best evidences for the existence of dark matter comes from the Hubble Space Telescope. Astronomers used gravitational bending of light from faint distant galaxies to map the distribution of mass in what appears to be the aftermath of a collision between two galaxy clusters. The blue color in the Hubble image shows the distribution of matter based on these measurements. In addition to the mass of the cluster in the center, a ring of unseen mass surrounds the galaxies. Computer simulations suggest that such a collision, occurring along Earth’s line of sight could produce this ring of dark matter.

What is dark matter? Does it really exist? Stay tuned.