Convection Currents

Convection Currents

In this experiment I will show you what convection currents are and how they work. don’t forget to check out my other videos and visit

Why NASA Scientists Observe the Sun in Different Wavelengths

Why NASA Scientists Observe the Sun in Different Wavelengths

This collage of solar images from NASA's Solar Dynamics Observatory (SDO) shows how observations of the sun in different wavelengths helps highlight different aspects of the sun's surface and atmosphere.

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This collage of solar images from NASA’s Solar Dynamics Observatory (SDO) shows how observations of the sun in different wavelengths helps highlight different aspects of the sun’s surface and atmosphere. (The collage also includes images from other SDO instruments that display magnetic and Doppler information.) 
Credit: NASA/SDO/Goddard Space Flight Center


Taking a photo of the sun with a standard camera will provide a familiar image: a yellowish, featureless disk, perhaps colored a bit more red when near the horizon since the light must travel through more of Earth’s atmosphere and consequently loses blue wavelengths before getting to the camera’s lens. The sun, in fact, emits light in all colors, but since yellow is the brightest wavelength from the sun, that is the color we see with our naked eye — which the camera represents, since one should never look directly at the sun. When all the visible colors are summed together, scientists call this “white light.”

Specialized instruments, either in ground-based or space-based telescopes, however, can observe light far beyond the ranges visible to the naked eye. Different wavelengths convey information about different components of the sun’s surface and atmosphere, so scientists use them to paint a full picture of our constantly changing and varying star.

Yellow-green light of 5500 Angstroms, for example, generally emanates from material of about 10,000 degrees F (5700 degrees C), which represents the surface of the sun. Extreme ultraviolet light of 94 Angstroms, on the other hand, comes from atoms that are about 11 million degrees F (6,300,000 degrees C) and is a good wavelength for looking at solar flares, which can reach such high temperatures. By examining pictures of the sun in a variety of wavelengths – as is done through such telescopes as NASA’s Solar Dynamics Observatory (SDO), NASA’s Solar Terrestrial Relations Observatory (STEREO) and the ESA/NASA Solar and Heliospheric Observatory (SOHO) — scientists can track how particles and heat move through the sun’s atmosphere.

We see the visible spectrum of light simply because the sun is made up of a hot gas – heat produces light just as it does in an incandescent light bulb. But when it comes to the shorter wavelengths, the sun sends out extreme ultraviolet light and x-rays because it is filled with many kinds of atoms, each of which give off light of a certain wavelength when they reach a certain temperature. Not only does the sun contain many different atoms – helium, hydrogen, iron, for example — but also different kinds of each atom with different electrical charges, known as ions. Each ion can emit light at specific wavelengths when it reaches a particular temperature. Scientists have cataloged which atoms produce which wavelengths since the early 1900s, and the associations are well documented in lists that can take up hundreds of pages.

Solar telescopes make use of this wavelength information in two ways. For one, certain instruments, known as spectrometers, observe many wavelengths of light simultaneously and can measure how much of each wavelength of light is present. This helps create a composite understanding of what temperature ranges are exhibited in the material around the sun. Spectrographs don’t look like a typical picture, but instead are graphs that categorize the amount of each kind of light.

On the other hand, instruments that produce conventional images of the sun focus exclusively on light around one particular wavelength, sometimes not one that is visible to the naked eye. SDO scientists, for example, chose 10 different wavelengths to observe for its Atmospheric Imaging Assembly (AIA) instrument. Each wavelength is largely based on a single, or perhaps two types of ions – though slightly longer and shorter wavelengths produced by other ions are also invariably part of the picture. Each wavelength was chosen to highlight a particular part of the sun’s atmosphere.

From the sun’s surface on out, the wavelengths SDO observes, measured in Angstroms, are:

  • 4500: Showing the sun’s surface or photosphere.
  • 1700: Shows surface of the sun, as well as a layer of the sun’s atmosphere called the chromosphere, which lies just above the photosphere and is where the temperature begins rising.
  • 1600: Shows a mixture between the upper photosphere and what’s called the transition region, a region between the chromosphere and the upper most layer of the sun’s atmosphere called the corona. The transition region is where the temperature rapidly rises.
  • 304: This light is emitted from the chromosphere and transition region.
  • 171: This wavelength shows the sun’s atmosphere, or corona, when it’s quiet. It also shows giant magnetic arcs known as coronal loops.
  • 193: Shows a slightly hotter region of the corona, and also the much hotter material of a solar flare.
  • 211: This wavelength shows hotter, magnetically active regions in the sun’s corona.
  • 335: This wavelength also shows hotter, magnetically active regions in the corona.
  • 94: This highlights regions of the corona during a solar flare.
  • 131: The hottest material in a flare.

SDO views the sun in 13 different ways, using two different instruments

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Each of the wavelengths observed by NASA’s Solar Dynamics Observatory (SDO) was chosen to emphasize a specific aspect of the sun’s surface or atmosphere. This image shows imagery both from the Advanced Imaging Assembly (AIA), which helps scientists observe how solar material moves around the sun’s atmosphere, and the Helioseismic and Magnetic Imager (HMI), which focuses on the movement and magnetic properties of the sun’s surface. 
Credit: NASA/SDO/Goddard Space Flight Center


Karen C. Fox
NASA Goddard Space Flight Center, Greenbelt, MD

20 interesting facts about science

20 interesting facts about science


The biggest (known) star in the universe – Canis Majoris, could fit 7 000 000 000 000 000 Earths.
In other words, if the Earth was the size of a pea, Canis Majoris would have a diameter of 2.7 kilometers.



Here’s how a sphere of whole water existing on the planet would look in relation to the Earth. (diameter of 1385km).



Fresh water in a liquid state (not counting the glaciers), is only 0.77% of the world water.


Heat Signature of Mimas – Saturn’s moon, is similar in shape to Pac-Man.



Here’s how far the first terrestrial radio transmissions reached  (112 years). Don’t we look ridiculously small?



Aerographite is so light that a lump the size of a bus could you pick up with one hand. It is built from a grid of hollow carbon tubes, so that it can move the load 40 000 times larger than its own weight.



Thinking about end of the world… Do you think any asteroid could crash into our planet? At the moment three objects are under the watchful eye of researchers. Two of them are small enough that the effects of the impact would be local. The biggest threat is the asteroid 1950 DA with a diameter of 1100 meters. Its impact could have global consequences. The chance of collision is low (about 0.33%), and the transition is believed to happen in 2088.


First planet outside our Solar System we discovered in 1990. You could think it’s because there is not many planets in the Universe. Actually it is believed there are 40 000 000 000 000 000 000 000 (40 and 21 zeros!) planets. Till now we discovered only about 800 planets.


Currently the largest known star is VY Canis Majoris. Its radius is 600 times larger than the radius of the Sun. However its mass is only 30 times bigger than the mass of the Sun.



The highest mountain in the Solar System is Olympus Mons located on Mars, its height  is estimated at 26 000 meters and the diameter at the base, is over 600 kilometers. On our planet such big mountain could not be created.




In the Solar System, there is one object larger than the planet, although he is not a planet. It’s Ganymede. It is a moon of Jupiter, which exceeds the size of Mercury!




Believe it or not, we are children of the stars and cosmic dust. If the stars did not explode in a spectacular way creating supernovas, there would be no elements necessary for us to live (eg coal). Because the stars are dying, can we live.


Solar prominence compared to Jupiter and Earth.



Every second the Sun creates the amount of energy that would be sufficient for mankind for next million years (with current needs).


Unaided human eye can see from our planet about 6000 stars. However, if we use binoculars, we will see 50,000. It seems a lot, but in the our galaxy is 400 billion stars.


If you were traveling through space at 99.999999% of the speed of light and came back after 10 years of traveling, on the Earth 70,000 years would pass.


Neutron stars are so dense that one tablespoon of the matter, weighs 90 billion kilograms!


If you would like to see the beginnings of the universe just turn on your TV and switch to the channel which no broadcast. Approximately 10% of the noise that we see is the background radiation, sent to us with the creation of the universe.


If you choose the scale that the Earth was the size of a pea, than Jupiter would be in a distance of over 300 meters, and Pluto – about 2,5 km from us (and would be the size of a bacteria so you wouldn’t even see it). The closest star – Proxima Centauri, the closest star (4 light years) would be 16 000 km from us.



If you got into Voyager, you would travel with a speed of 56.000km/h How long would it take you to reach anywhere?

– to the nearest object – the Moon – 6 hours

– to the Sun – 111 days

– to the nearest Star outside Solar System – Proxima Centauri – 77 000 years !

– to Pole Star – 8 000 000 years of travel

– to the nearest galaxy – Andromeda – 48 billion years (to remind you – the universe is 13,7 billion years old


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Inspiration: Ilgesu



Structural Colour, Soap Films, & Nanotech Security From Butterflies

Structural Colour, Soap Films, & Nanotech Security From Butterflies

Scientists are being inspired by nature to design the next generation of security devices. Arrays of nanoscale holes create beautiful reflected colours that are almost impossible to forge. This video was supported by TechNyou – check out their series on logical fallacies:

Soon these nanoscale security devices could replace holograms. They are many times more reflective than holograms, and although the structures are smaller scale, they are lower aspect ratio and therefore easy to manufacture in bulk.

The electron wiggle simulation is from PhET, the best physics simulations ever:

Special thanks to Thomas from Copenhagen who showed me around the city including the science museum where he assisted with the soap bubble demonstration.

Clint Landrock is the Chief Technology Officer for Nanotech Securities:

Music is “Firefly in a Fairytale” by Gareth Coker

DNA Hydrogel Collapses, Then Remembers Original Shape

DNA Hydrogel Collapses, Then Remembers Original Shape


To learn more about this material, go to Nature can do a lot of spectacular things. But some researchers are designing materials that go beyond what Mother Earth is capable of. These substances are called metamaterials. Now, scientists from Cornell University have designed a new metamaterial called a DNA hydrogel that can collapse into a puddlelike state but then retake its original shape when submerged in water. Like the robot assassin T-1000 in “Terminator 2,” the researchers think their new gel might one day flow through a narrow opening and take shape again on the other side. In the meantime, however, they’re eyeing the material for use in drug delivery and electrical circuits.