Orbit of Earth&Moon around Sun

We all know that the moon orbits the earth. (Well actually they both orbit about their common center of mass (barycenter), which for the earth-moon system lies about 1500km inside the Earths center, so the center of mass of the Earth-Moon system is actually inside the Earth due to the Earth being much much more massive, so we can approximate and say that the moon is orbiting about the Earth). Anyway, just imagining that the Moon orbits about the Earth and then the fact that (similar mass argument for the Earth-Sun system) the Earth orbits about the Sun, what do you think the Earth-Moon orbit around the sun would look like? This is actually a very interesting and hard to visualize question. Just try it.

Will the Moon ever be going backwards around the Sun, relative to Earth, considering that it is going around the Earth, as the Earth goes around the Sun. The answer is no.
Not like this: https://haplofromnexus.files.wordpress.com/2012/11/moon_sun_wrong.jpg
Like this: https://haplofromnexus.files.wordpress.com/2012/11/moonorbitdiagram.jpg
Or even better like this: https://haplofromnexus.files.wordpress.com/2012/11/moon_synodic_cycle.jpg

There are no rearward loops in the Moons solar orbit, due the fact that the orbital velocity of the Moon about the Earth (1km/s) is small compared to the orbital velocity of the Earth about the sun (30km/s). Also because the suns gravitational pull on the moon is over twice as great as the Earths pull on it, the Moons orbit around the Sun is always convex.
Have an orbital day,
Mete.

You can read more about this topic here:
http://www.math.nus.edu.sg/aslaksen/teaching/convex.html
http://en.wikipedia.org/wiki/Orbit_of_the_Moon

Seeing round a corner (Femto-Photography)

Can you see round a corner, without using a mirror?
Well, apparently using femto-photography you can. Femto-Photography is a term describing ultra high speed imaging. And when I say ultra, I mean ULTRA. It was first used on objects by a team at the MIT Media Lab lead by Ramesh Raskar. You can watch the video below, I’ve provided a link to it (it is amazing).

Basically we watch light exit a laser and travel for one trillionth of a second and bounce around and disperse into darkness, it all looks quite great. If instead of a laser pulse it was a bullet fired from a gun we were watching at this time scale, we would be sitting watching it for 1.5 years. Light is fast, the fastest (c = 3×10^8 m/s), about a million times faster than a bullet.

Seeing around a corner is done by tracking the path differences of individual photons fired from the camera bounced off a wall to the object back to the wall then back to the camera. Because the camera is so ridiculously accurate the object in the other room is basically replicated on the screen to exact shape, to understand better watch the video by Ramesh Raskar’s team.
So basically, let there be light..
Mete.

Link to video:
http://www.youtube.com/watch?v=Y_9vd4HWlVA
Further Reading:
http://web.media.mit.edu/~raskar/trillionfps/

One trillion frames per second is truly an amazing concept…

Washing your Hands (The secret behind it)

Do you know how washing your hands with soap actually cleans them?
The question is what differs washing with soap from washing with plain water?

Washing with soap and water is a scenario in which you without realizing exploit the dipole nature of water. Grease and oil are made up of non-polar molecules, so they are not attracted to water which is a highly polar molecule. Soap on the other hand contains long molecules called surfactants. In these molecules, because they are so long, while one end exhibits a polar nature the other end of the molecule exhibits a non-polar nature. The non-polar end of these soap molecules can attach to non-polar substances like grease or oil, and then the other, polar, end of the molecule is attracted to the polar water molecules and thus binds itself to them. Therefore soap acts like a bridge between the dirt (grease, oil..) and the water. When we rinse our hands the soap and all the grease and oil that has attached itself to the soap go down the drain. Voila, clean hands.
Have a nice clean day,
Mete.

If you want to read more about the nature of soap here are a few links:
http://chemistry.about.com/od/cleanerchemistry/a/how-soap-cleans.htm
http://www.chemistryexplained.com/Ru-Sp/Soap.html#b

Auroras off the coast of Iceland (Northern Lights)

Auroras are truly magnificent sights, they are seen in the arctic/antarctic regions of the world. When observed in the north hemisphere they’re called Aurora Borealis (aka Northern Lights). They’re named after the Roman Goddess of dawn (Aurora) and the Greek name for the north wind (Boreas). They illuminate the northern horizon in a beautiful greenish glow. They look surreal, but no, they are completely real!

A brief scientific explanation of this beautiful phenomenon: (links below for further reading):
Aurora’s are results of photon emissions in the upper part of the atmosphere (thermosphere – above 80km). Either a Nitrogen or an Oxygen molecule is ionized(excited) by colliding with a solar wind or magnetospheric particle being accelerated along the earths magnetic field. Then the excited “extra” energy is lost by the emission of a photon, which for an Oxygen emission results in a green color (as seen in the picture) and for a Nitrogen emission results in a blue/red color depending on the exact mechanism. This is my brief summary of the subject, just to get you interested, if the picture has not been sufficient that is.
Mete.

You can read in more detail about auroras here:
http://en.wikipedia.org/wiki/Aurora_(astronomy)
http://www.exploratorium.edu/learning_studio/auroras/happen.html

Here are some pictures of really amazing auroras:
http://news.nationalgeographic.com/news/2012/10/pictures/121023-auroras-northern-lights-science-space-penguins-meteor/
http://www.telegraph.co.uk/earth/earthpicturegalleries/7147251/Aurora-borealis-awesome-pictures-of-the-northern-lights-in-Norway-taken-by-Bjorn-Jorgensen.html