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Beautiful Aurora Display

It’s been a while I posted something, consider this a semi-hiatus from blogging. I will try to post something from time to time. I have posted several posts on Auroras. Here is another one with video and pictures taken by astronauts on ISS while passing over Indian Ocean on Sep 17th 2011. They took several  images and compiled a video which shows spectacular Aurora display. This particular Aurora display was a result of Coronal Mass Ejection event which occurred in the Sun on Sep 14th 2011, leading to stirring of the earth’s magnetic field and excitation of nitrogen and oxygen molecules in earth’s atmosphere. Greenish part of the Aurora glow is contributed by emission from excited oxygen molecule while blue or purple glow is from nitrogen molecule. Enjoy the Video. Towards the end of the video you can notice some specks and bright glows on earth’s surface which are infact forest wild fires and agricultural fires in Australia.

Image and video credit: NASA

Leave a Comment October 27, 2011

Symphony of Science: The Quantum World

Enjoy the symphony of quantum world featuring Morgan Freeman, Stephen Hawking, Michio Kaku, Brian Cox, Richard Feynman, and Frank Close.

Video credit: http://symphonyofscience.com

Leave a Comment September 7, 2011

Hurricane Irene’s life span

Hurricane Irene spanned from Caribbean to Canada and lasted for more than a week. NASA/NOAA satellite GOES-13 kept a track of the hurricane and NASA posted a video of the hurricane dating Aug 21st to Aug 29th which covers almost entire life-span of the hurricane. In the video you can see the formation of eye (at about 30 seconds in the video). Right after the formation of eye, you can see a burst of white clouds on the right of the eye which then merges with the core of the hurricane. This burst is due to warm air rising the clouds , also called as overshooting tops, and resulting in severe rainfall. Hurricane Irene at it’s strongest was a category 3 hurricane and turned out to be one of the top ten most destructive hurricanes in the history of US since 1980. About 27 lives were lost, entire transportation system in east coast was affected and more than 5 million people lost power.

Leave a Comment September 5, 2011

Motion And Phases of Moon

While people are enjoying today one of the longest lasting lunar eclipse since 2000 (about 100 minutes long), let’s watch this beautiful video created by folks at NASA Goddard Space Flight Center (see below) using data collected by Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO). In the video you can see various phases and movement of moon during the course of one year; one month of movement has been compressed into 12 seconds. As we know, we are able to see only one face of the moon from earth (moon and earth are phase-locked– rotation time of moon is same as it’s revolution time around the earth- about 27 days), in the video it is clearly evident that only one side is visible to us. Since we get to see the moon from different angles owing to it’s tilt and elliptical shape of the orbit, in the video it appears to us as if moon is wobbling. In technical terms we call that wobbling as “liberation”. Because of liberation, we are able to see little bit more than half of the moon’s surface, close to 60%. Due to elliptical orbit, moon also appears to rock back and forth from us (perigee- nearest position, apogee- farthest position). You can also observe different phases of moon such as new moon and full moon and their variations in different months. Enjoy the video, I will be uploading some cool videos or pictures from today’s lunar eclipse event later on.


Video/Image credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

Leave a Comment June 15, 2011

‘Living Laser’ Created Using Jellyfish Protein And Human Cell

In a new study published today in Nature Photonics, scientists from Wellman Center for Photomedicine and Harvard Medical school have developed a “living laser” by using biological materials- human cell and jellyfish fluorescent protein. In order to get coherent beam of light from a lasing device, three things are required- a pump source (typically flash lamp,  electric current or other laser source), a ‘gain media’ for amplifying the source (optical gain) and an ‘optical cavity’ for concentration and alignment of the laser beam. Typically, crystals, dyes, gas mixtures and even alcohol have been used as gain media to amplify the light. Pumping source produces population inversion in the gain media  wherein majority of the atoms and molecules are in excited state. When a photon of appropriate wavelength interacts with such a system of atoms/molecules, stimulated emission occurs. In a very novel approach, researcher Malte Gather has used Green Fluorescent Protein (GFP) and inserted the protein in living human embryonic kidney cell. Bioluminiscent GFP was  first isolated from jellyfish in 1962 which ultimately resulted in Noble prizes for it’s discoverers. The kidney cell-GFP combo (gain medium) was then  kept in between an optical cavity made of mirrors kept 20 microns apart. The dimension of single cell gain media was also about the same. When researchers hit the cell with low energy pulses of blue light using a microscope, typical diffused ordinary fluorescence was observed. But after reaching a certain threshold of input energy (~0.9 nJ), the light output from the cell changed drastically and resulted in bright, directional and narrowband emission of green light, which are the characteristics of a laser beam. Certain regions of cell showed intense lasing action (as shown in picture above) which occurred at different but close range of wavelengths (~514-519 nm). Researchers also reported that even after prolonged lasing action, the cell was still alive. The lasing action lasted for few nanonseconds and was easily detectable. The cell was able to lase about 100 pulses at excitation pulse energy of 50 nJ after which photobleaching occurred and depleted the GFP. But an interesting aspect of GFP infused cell is that the cell is able to heal itself and replenish GFP with time.

Here is an output emission spectra of the laser filled with purified GFP solution when pumped using different wavelengths of light. As can be seen that the output spectra is independent of the pump wavelength. This spectra tells two things i) independence of excitation wavelength on the emission rules out any stimulated scattering process as an explanation for lasing action by GFP, ii) FWHM ( Full Width at Half Maximum) of about 12 nm signifies the presence of  simultaneous oscillations of various longitudinal modes.

Next figure shows that replacing the GFP solution with GFP-transfused cell resulted in much narrow output spectra. At energy threshold of 0.9 nJ, single emission peak was observed at 516 nm (FWHM <0.04 nm). As the energy was increased, multiple emission peaks were observed which can be attributed to multiple longitudinal oscillation modes. The spectral spacing between these emission line was in the range of 5 nm.

Researchers speculate that the resulting light could be used to study various intercellular processes. Before producing output light, the light travels several times through the cell placed inside the optical cavity and the resulting lasing light should contain information regarding the intercellular processes. Another possible use could be to produce such lasing beams inside the body itself to kill certain cancerous cells .

Creators of living laser, Yun and Gather,  have some broad and speculative ideas about how the technology might be used.

They suggest that biologists could turn cells of interest into lasers to study them. The light produced has a unique emission spectrum related to both the structure of the cell and the proteins inside it. “By analysing the pattern you can get some idea of what is happening inside the cell,” says Yun.

The researchers also suggest possible medical applications. Doctors today shine lasers into the body to gather images or to treat disease by attacking cells. Yun thinks that lasers could instead be generated or amplified inside the body, where they could penetrate the relevant tissues more deeply. [Nature News]

Image credit: 1) Malte Gather | Nature Photonics | Wired 2) From the supplement files of the article provided on Nature website 3) Snapshot of the plots as seen at Nature website

Reference: Single-cell biological lasers: Nature PhotonicsYear (2011) DOI: 10.1038/nphoton.2011.99

Leave a Comment June 13, 2011

Potrait of Endeavour And International Space Station

Here is an amazing picture of space shuttle endeavour parked at the International Space Station. The image was taken on May 23rd by ESA astronaut Paolo Nespoli while he was leaving the space station aboard on Russian spacecraft Soyuz. His spacecraft was at a distance of about 600 feet when this picture was taken. Endeavour helped in building up the station over the past decade and this was the last space trip of Endeavour. Truly an amazing image. By the way if you ever wondered how parking your vehicle in space would look like, now you got the idea! If you want more of this, here is a high quality video taken by Nespoli.


Image and video credit: NASA

Leave a Comment June 8, 2011

Lost In The Crowd

Till now, 283 posts have been posted in this blog– some of them good, some not so good, some got numerous hits wile some were lost in the crowd. I will be recycling some of these posts in coming days. In today’s post, I will be re-posting 7 posts which, according to me, were good ones but were  lost in the crowd and didn’t get as many hits as they should have. So here they are:

  1. The Courageous Life of Sophie Scholl Now, who is Sophie Scholl? Sohpie Scholl was a member of non-violent student resistance movement against Nazi rule in Germany. The group called itself “White Rose” which was mostly based in University of Munich campus and its main activity was printing and distributing leaflets denouncing Hitler’s rule, which was equivalent to asking for death sentence in Hitler’s regime.
  2. Invictus: The Unconquered Ones Gandhi, Mandela, Martin Luther King were all Invictus, the unconquered ones, and they were the masters of their souls. The poem “Invictus” by William Henley probably describes very well the struggles of such souls amongst all the obstacles, still emerging victorious.
  3. Hole-Punch Clouds: Mystery Solved Any guesses what punched that hole in the cloud? Well, researchers have been looking for the answer for a while and airplanes have been the main suspect for this phenomenon.New research studyconfirms that planes, both propellers and jet planes , can cause formation of these shapes in the clouds named as “hole-punched clouds ” or “punched hole clouds” as a result of enhanced precipitation effect. These clouds have also been linked to UFO sightings in past, most famous one being inMoscow during October 2009.
  4. Wait For It…Wait For ItPatience pays, Don’t give in to temptations, Have Self-control: we have been told since our childhood. Well, depending on how much self control or patience we have, determines our success in life. To study these effects and what mental processes lead to self control or delayed gratification, psychologist Walter Mischel conducted a very famous Marshmallow experiment with a group of few 4 year old kids in Stanford in 1960.
  5. Time To Tickle You Tickling is a very interesting sensation, it can burst you into laughter and on the other hand it can make you agitated as well. We all have tickled someone or have been tickled either by parents or siblings or friends. It’s also interesting to note that you can not tickle yourself implying that an element of surprise is very important.
  6. Prime is in Nature Magicicada is one of the genus of cicada species and are primarily found in eastern US and they have a very interesting periodic life cycle pattern. They follow either a 13 or 17 year life cycle pattern where after hatching from the eggs, and lying under the ground for 13 or 17 years, all of them emerge at once on the surface. Emergence of all the adult cicadas after 13/17 years is well synchronized.
  7. Photoemission Delay Time Photoelectric effect has been known to us for a long time. Heinrich Hertz first observed this phenomena in 1887 where a material absorbs electromagnetic radiation and emits electrons. While most of details are clearly understood, one aspect which has been missing is the delay time in emission of electrons after the matter absorbs photon.

Image credit: Flickr user Missbng | Used under Creative Commons License

1 Comment June 3, 2011

Mars Rover Spirit Is Officially Dead

After exploring surface of Mars for about 7 years, Spirit has been officially declared dead for all scientific purposes. Spirit started it’s Martian journey on Jan 2004 to carry out it’s scientific mission which was supposed to last for 90 days. But Spirit surpassed all the expectations and continued exploring Mars for another seven years. It stopped communicating on Mar 2010 and attempts were being made by NASA to communicate with the rover. Finally, NASA concluded it’s attempts of contacting Spirit today.

“We’re now transitioning assets to support the November launch of our next generation Mars rover, Curiosity,” said Dave Lavery, NASA’s program executive for solar system exploration. “However, while we no longer believe there is a realistic probability of hearing from Spirit, the Deep Space Network may occasionally listen for any faint signals when the schedule permits.” [NASA]

Great job Spirit!  Here is xkcd’s take on spirited Martian journey of our beloved scientific instrument:

Image credit: 1) Artist concept of Mars rover| NASA/JPL/Cornell Univ 2)Xkcd

Leave a Comment May 25, 2011

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