Monthly Archives: April 2016

Where Do Stars Come From?

Where do stars come from? The short answer is: gravity. All objects with mass experience gravitational attraction to each other. That includes you & the Earth, you & me, every person on our planet, and every star in the cosmos. So, why aren’t we pulled in all directions? Gravity depends on two things: mass and distance. The bigger an object is, the stronger its influence. The farther it is from you, the less you’re affected by its pull. Stars have plenty of mass, but they’re so far away that their gravitational effect on us is negligible. You and I could stand next to each other, but we just aren’t massive enough to pull significantly on each other compared to the much stronger attractive force Earth exerts on our bodies.

Orion Nebula

The Great Orion Nebula, visible to the naked eye as part of Orion’s dagger, is a massive space-cloud system and a productive stellar nursery. Image credit: UMass/2MASS/IPAC

In deep space, it’s a different story. In the absence of larger gravitational influences, even dust particles pull each other closer. It’s this quiet, dark, and delicate dance that gives rise to the stars we see in the night sky. Nebulae are massive space clouds of gas and dust. Within these clouds, turbulence makes some areas denser than others. When a dense knot of dust reaches critical mass, it collapses under its own gravitational pull, heating up and becoming a protostar. This spinning collection of hot, dense debris drags nearby particles along with its rotation, and an embryonic solar system is formed.

Einstein’s theory of relativity describes spacetime as a three-dimensional fabric that can be stretched in a fourth dimension. The way that massive objects stretch the fabric of spacetime explains their gravitational pull on each other. That’s tough to visualize, but a two-dimensional model that stretches in 3D helps us to wrap our heads around the idea.  

Particles of water vapor model the behavior of dust in a nebula.

When we place a heavy sphere in the center of a sheet of stretchy fabric, it pulls the surface down. Drop marbles or BBs onto the fabric and they spiral around and around before coming to rest at the lowest point. The same thing happens with water vapor: it spirals to the spot where the gravitational potential is lowest– the heavy object in the middle.

This model of spacetime provides a simple, fairly accurate illustration of the way individual stars form in nebulae.

Written By: Caela Barry

The Greatest Telescope That Almost Wasn’t

Why put a gigantic telescope in space? It’s a common misconception that Hubble was placed in orbit to be closer to the stars. Really, the difference in distance between our planet’s surface and low Earth orbit is negligible compared to how far away Hubble’s research targets are. The great advantage of a space telescope is its location outside of our atmosphere.

Light from faraway objects is distorted as it passes through the air on the way to ground-based telescopes. The universe looks much clearer with no atmosphere in the way. When Hubble launched in 1990 it was expected to deliver incredibly crisp images, hubble_in_orbit1but the school-bus-sized satellite’s first pictures were blurry. Something had gone terribly wrong.

Painstaking analysis by engineers on the ground revealed the source of the blur: spherical aberration. Hubble’s massive primary mirror, supposedly the most precise optical device ever created, had been meticulously ground into slightly the wrong parabolic shape, the result of a faulty testing mechanism. The mirror was off by about 1/50th the width of a human hair– a tiny error with massive consequences.

With hefty research expectations, billions of dollars, and NASA’s reputation on the line, project scientists snapped into action. A backup version of the Wide Field Planetary Camera, the instrument that would go on to produce Hubble’s most iconic images, was retrofitted with corrective optics. An ingenious contraption of moving mirrors was devised to refocus light from the primary mirror as it entered four other detectors. All this was designed and assembled on the ground, 347 miles below the faulty hardware. The math had to be perfect.

Thornton4thEVAKathryn Thornton on the 4th EVA of STS-61. Credit: NASA

Seven astronauts undertook an audacious mission to repair the giant scope. The STS-61 crew completed a record-setting five back-to-back spacewalks for a total of over 35 hours of EVA time. Their work was a resounding success. Hubble had been redeemed, and NASA vindicated.

Hubble Servicing Mission 1 stands today as a masterpiece of engineering, determination, and teamwork. It corrected the vision of humanity’s most powerful eyes on the cosmos, clearing the way for decades of compelling imagery and game-changing research.

Screen Shot 2016-04-24 at 12.11.41 PMHubble’s unprecedented depth of field allows scientists to peer into the early history of the universe. Credit: NASA

Today, the space telescope addresses fundamental questions about the age and nature of the universe. Its stunning documentation of faraway phenomena brings the wonder of space down to Earth. STS-61 narrowly salvaged public confidence in America’s ability to effectively explore space by turning Hubble’s story from one of crushing defeat to one of redemption.
Diagram source ; all other images cred NASA

Written By: Caela Barry

Make Your Own Cloud Chamber

Clouds usually form when water molecules clump together on small particles of dust in the air. These particles are called condensation nuclei. In clean air, they’re hard to come by, so clouds don’t form easily. If conditions are very humid, the air can become supersaturated, or rich with water molecules that would form a cloud if condensation nuclei were available. With nothing to grab on to, though, the molecules stay suspended and invisible… that is, until something disturbs the system.

StJohnFisherCollege contrail Image courtesy of St. John Fisher College.

You’ve probably seen this happen before! Jet planes leave contrails, or condensation trails, when they introduce exhaust into supersaturated areas of Earth’s upper atmosphere. RochesterDecayThis is a common example of foreign particles triggering condensation. Air molecules themselves can also act as condensation nuclei if they’re electrically charged. One way that air molecules become ionized (or charged) is by colliding with radiation from outer space.

Earth receives a constant shower of cosmic rays. Most primary radiation that reaches our atmosphere comes in the form of ultra-high-energy protons, followed in frequency by helium ions and a smattering of other particles. These decay in the upper atmosphere into elementary particles, which go on to ionize thin streaks of the lower atmosphere as they continue hurtling Earthwards. In a supersaturated environment, the newly charged air molecules act as condensation nuclei, leaving a cloudy trail in the wake of the decayed cosmic radiation. The image at left (courtesy of the PARTICLE program at Rochester University) shows primary rays decaying into pions, muons, neutrinos, and gamma rays.

Below, a streak of mist reveals cosmic radiation as it travels through our tabletop cloud chamber. To see cosmic rays for yourself, you’ll need a contained, supersaturated vapor and a bright light source to highlight cloud trails. Science Friday has an excellent step-by-step instruction set that helped us a lot in our DIY design process– check it out!


Written By: Caela Barry

Da Vinci’s Parachute

Leonardo da Vinci was a mind ahead of his time. He didn’t live to see the realization of most of his thousands of pages of inventor’s notes and sketches, but his vision was practical and insightful. Modern experimenters have used updated materials and technology to bring many of his designs to life. His innovations in structural engineering influence present-day bridges, helicopters, tanks, and more.


Artist Vebjorn Sand made this bridge a reality in modern Norway 500 years after da Vinci first designed it. Its 740-foot span was unprecedented at the time of its invention. Image credit: North Coast Cafe, South.

In honor of his birthday, we set out to find and build a simple, DIY-friendly da Vinci invention. His war machines and flying devices are both intricate and clever. One project stood out as more approachable than the rest: the da Vinci parachute.









 Adrian Nicholas, the professional skydiver who tested the Da Vinci parachute in 2000, and Leonardo’s original schematic sketch. Left image courtesy of

Hundreds of years before the invention of the modern parachute, da Vinci conceived of a pyramid-shaped canvas tent that would slow the fall of a heavy object. He envisioned the structure protecting jumpers from burning buildings. It’s a far cry from today’s ultra-lightweight and compact drag technology, but his design is a practical one– mostly. Daredevil Adrian Nicholas constructed and tested the unusual chute in 2000. Its descent from a hot air balloon 10,000 feet above Earth’s surface was slow and smooth, and the chute landed with minimal damage. Nicholas nonetheless cut loose from the canvas tent at an altitude of 3,000 feet and finished his jump with modern gear to avoid being injured by the 187-pound structure on landing.


Our da Vinci experiment began with a prototype made of four sheets of printer-size paper and a 15g weight. Next, we scaled our chute up, cutting each side of the pyramid from a sheet of poster paper. We didn’t reach the human-carrying level, but did drop an otherwise unprotected egg from a second-story balcony– it survived!square corners

We’d definitely recommend trying this at home. The size and shape of the parachute are deceptive, and its stately, surprisingly stable flight is a lot of fun to see in person. Consider reinforcing the corners of your chute’s base with right angles made out of paper or another structural element to help it keep its square shape, as shown on the right. Happy testing!

Written By: Caela Barry

DIY: The Invincible Bag

What do DNA, RNA, styrofoam, and Ziploc bags have in common? They’re all made of polymers! Polymers are macromolecules, or long chains of repeated small parts. They’re stretchy, tough, and omnipresent– polymers even encode your body! Individual molecules are too small to be directly observed by humans, but we can see some of the properties of polymers in action with a simple experiment.

PolymerizationIndividual molecules of nylon bond together to form a polymer.

When a sharp pencil tip pushes between the polymers, they stretch tight around its surface. This snug plastic hug keeps the water sealed inside, and the pressure of the water helps keep the seal in place. You’re not damaging the individual molecules the bag is made up of, you’re just separating them!

Invincible BagWatching this really feels like a trick, so this is definitely a great one to try it at home! All it takes is some sharp pencils, a ziploc bag, and some water.

Take the ziploc bag and fill it up most of the way with water. Make sure to leave a bit of an air bubble at the top, or the bag will leak due to extra pressure created by the pencils displacing the water. Then take the pencils and stab them through the outer wall of the bag. It feels awesome, and it looks cool too!

Screen Shot 2016-03-30 at 11.22.27 AMHow many pencils can you stab through one bag?

Written By: Scott Alton

DIY: Make a Magnetic Slime Monster!

Did you know that our planet is a giant magnet? It’s true! Without Earth’s magnetic field, compass navigation would be impossible. The field also shields us from cosmic radiation, directing most solar wind far around our planet. In space, large objects are generally too distant from each other to be noticeably pulled or pushed by the magnetic force between them. Here on the surface of the Earth, we have the advantage of being able to bring magnetic materials close together, which makes for some awesome experimental science!

It shouldn’t surprise anyone that iron sticks to magnets. Really, that’s all this demonstration is showing us. However, crazy, alien-like slime is a little cooler than slapping a magnet on a refrigerator. It’s lots of fun to make, and it’s not too difficult!

Mag Slime SetupHere is what you will need to make this at home:

  • A place where it is okay to make a mess
  • A mixing bowl, a small cup or beaker, and a spoon
  • A full container of school glue
  • Borax
  • Water
  • Iron filings and a neodymium magnet
  • Towels

Start by pouring the glue into the mixing bowl. Then, to get all of the glue out of the bottle, fill it with water. Shake it a lot to mix it up, and pour that into the bowl as well. Sprinkle some iron filings into the glue and water, keeping in mind that you can always add more later. It should look something like this:

Screen Shot 2016-04-04 at 1.47.25 PM

Next, fill your cup or beaker about halfway with water. Slowly add borax, stirring it in until it dissolves completely. Pour this solution into the bowl and start mixing. We started mixing with a fork, but then decided to get our hands dirty!

Slime Mixing gifStirring this mixture feels weird! It slowly clumps into squishy, almost cloth-like strips, but those strips don’t initially like to stay together. That’s okay! Keep squishing them around in the bowl. We found that in the end we had too much water or not enough patience (likely both) so we ditched the extra liquid, pulled all of the solidified bits together, and started molding them into a ball.

At this point, the magnet can be introduced. Note that neodymium magnets are very strong! They will grab anything metal tightly and suddenly. Usually, this only causes surprise, but it can lead to injury. Be careful, and keep this experiment away from all metal or otherwise magnetic objects.

Magnetic Slime gif

Due to the bits of iron in the slime, the magnet is attracted to it. Even cooler, if the magnet and slime are placed close together and left alone, the slime will be attracted to the magnet and cover it entirely! Note that the magnetic slime attack above is sped up a lot. The slime actually takes a few minutes to completely swallow the magnet.

If this isn’t happening with your slime, try adding more iron. We did this several times. Simply sprinkle in some more iron and continue mixing it in until you can’t tell where the iron was added. Don’t be afraid to experiment. After all, this is science!

Written By: Scott Alton, Caela Barry

Candle-Powered Seesaw – It’s Physics

Archimedes famously claimed that, given a lever, he could move the whole world. Why so confident, Archimedes? Levers take advantage of a rotational force called torque. You use this force to make your life easier every time you open a door, paddle a boat, turn a wrench, hit a baseball… the list is endless! Here’s the common thread connecting these mechanisms: if you want to turn something, it helps to apply force as far as possible from the axis of rotation.

LeverOhioMost people know this intuitively (or at least through a lifetime of practice). Where do you grip a wrench as you’re tightening a nut? Probably near the end! Try opening a door by pushing right next to the hinges, and it becomes clear why the doorknob is usually all the way on the opposite edge.

A seesaw — or lever — is just an extension of the same idea. One way to make a heavy load manageable is to put it on the other side of a center of rotation, or fulcrum. Then, the farther away the pusher moves, the easier their job becomes. In other words, it’s much easier to move a seesaw by pushing at one end than near the middle. (Lever diagram courtesy of Ohio University.)

So, using a long handle is one way to make rotating (or lifting) an object easier. Of course, it also helps to increase the pushing force, or to make the target load lighter– mass makes a difference, too!


The candle seesaw shows the effects of changing the mass at each end of a balanced, rotating system. As the lower candle burns, wax drips off, and the candle becomes lighter. The top candle melts, too, but its wax runs down its sides and quickly cools, so the overall mass of that candle doesn’t change. When the bottom end is light enough, the top end swings down, it begins to lose wax itself, and the process repeats.

Written By: Caela Barry


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