VITUK

nasa:

On May 25, 2017, the moon photobombed one of our sun-watching satellites by passing directly between the satellite and the sun.

The Solar Dynamics Observatory, or SDO, orbits Earth and watches the sun nearly 24/7 — except when another body, like the moon, gets in the way. These lunar photobombs are called transits, the generic term for when any celestial body passes in front of another.

Transits are one way we detect distant worlds. When a planet in another star system passes in front of its host star, it blocks some of the star’s light so the star appears slightly dimmer. By monitoring changes in a star’s light over time, scientists can deduce the presence of a planet, and even determine what its atmosphere is like. This method has been used to discover thousands of planets, including the TRAPPIST-1 planets.

SDO sees lunar transits about twice a year, and this one lasted about an hour with the moon covering about 89 percent of the sun at the peak of its journey across the sun’s face.

When they’re seen from Earth, we call lunar transits by another name: eclipses.

Solar eclipses are just a special kind of transit where the moon blocks all or part of our view of the sun. Since SDO’s view of the sun was only partially blocked, it saw a partial eclipse. Later this year, on Aug. 21, a total eclipse will be observable from the ground: The moon will completely block the sun’s face in some parts of the US, creating a total solar eclipse on a 70-mile-wide stretch of land, called the path of totality, that runs from Oregon to South Carolina.

Throughout the rest of North America — and even in parts of South America, Africa, Europe and Asia — the moon will partially obscure the sun, creating a partial eclipse. SDO will also witness this partial eclipse.

Total solar eclipses are incredible, cosmic coincidences: The sun is about 400 times wider than the moon, but it also happens to be 400 times farther away, so the sun and moon appear to be the same size in our sky. This allows the moon to completely block the sun when they line up just right.

Within the path of totality, the moon completely obscures the sun’s bright face, revealing the comparatively faint corona — the sun’s pearly-white outer atmosphere.

It’s essential to observe eye safety during an eclipse. You must use proper eclipse glasses or an indirect viewing method when any part of the sun’s surface is exposed, whether during the partial phases of an eclipse, or just on a regular day. If you’re in the path of totality, you may look at  the eclipse ONLY during the brief moments of totality.

A total solar eclipse is one of nature’s most awe-inspiring sights, so make your plans now for August 21! You’ll also be able to see the eclipse cross the country that day through the eyes of NASA – including views of the partial eclipse from SDO – on NASA TV and at nasa.gov.

Learn more about the August eclipse — including where, when, and how to safely see it — at eclipse2017.nasa.gov and follow along on Twitter @NASASun.

neurosciencestuff:

Patients with spinal cord injuries might one day regain use of paralyzed arms and legs thanks to research that demonstrates how limbs can be controlled via a tiny array of implanted electrodes.

(Image caption: The Utah Slated Electrode Array. Credit: University of Utah)

The work focused on controlling electrical stimulation pulses delivered to peripheral nerve fibers. When a patient is paralyzed, one of the possible causes is damage to the spinal cord, which along with the brain makes up the central nervous system. The brain is working, and so are motor and sensory nerves in the peripheral nervous system, but electrical signals can’t flow between those nerves and the brain because of the spinal cord injury.

That communication problem is what researchers sought to address, through experiments that involved transmitting precisely controlled electrical pulses into nerves activating plantar-flexor muscles in an ankle of an anesthetized cat.

V John Mathews, professor of electrical engineering and computer science in the Oregon State University College of Engineering, lead researcher Mitch Frankel, then a Ph.D. student at the University of Utah, and three other researchers, all faculty members at Utah, conducted the study. Findings were recently published in the journal Frontiers in Neuroscience.

Researchers sent the pulses using an optimized PIV controller – proportional-integral-velocity – and the cat’s nerves received them via a 100-electrode array whose base measured just 16 square millimeters; it’s known as the Utah Slanted Electrode Array, named for where it was developed and the angled look produced by the electrode rows’ differing heights.

Thanks to specific electrodes being able to activate the right nerve fibers at the right times, the controller made the cat’s ankle muscles work in a smooth, fatigue-resistant way.

The results suggest that someday a paralyzed person might be equipped with a wearable, smartphone-sized control box that would deliver impulses to implanted electrodes in his or her peripheral nervous system, thus enabling at least some level of movement.

“Say someone is paralyzed and lies in bed all day and gets bed sores,” Mathews said. “Early versions of this technology could be used to help the person get up, use a walker and make a few steps. Even those kinds of things would have an enormous impact on someone’s life, and of course we’d like people to do more. My hope is in five or 10 years there will be at least elemental versions of this for paralyzed persons.”

While this particular study focused on helping the paralyzed, a related research area involves amputees: neuroprostheses that can be controlled by thought based on decoding what goes on electrically inside a person’s brain when he or she wants to, for example, move his or her arm or leg.

“We can learn from the brain what the intent is and then produce the signals to make the movement happen,” Mathews said. “Another way to get the control information is from the peripheral nerves,” via electromyography, a diagnostic procedure for evaluating muscle and nerve health.

Generally, Mathews said, an electromyogram can produce the necessary control information.

Putting sensors in a person’s brain, either by deep brain implant or just inside the cranium, is another way to crack the intent code. Electroencephalography – electrode plates attached to the scalp that upload the brain’s electrical activity to a computer – can be used as well.

“There are a lot of things going on right now in the prosthetic arena,” Mathews said.

teded:

In order to celebrate Pi Day, we TED-Ed nerds are bringing you 3 fun facts about our favorite irrational number!

1. Pi is infinite! To write it out, you’d begin with 3.14159 and continue on….forever! That’s why, instead of trying to write out an infinite number of digits every time, we just refer to it using the Greek letter, Pi. 

2. Pi is an irrational number, or a number that can never be expressed as a ratio of 2 whole numbers.

3. Scientists have used Pi to calculate the density of our entire universe, which has infinitely less stuff in it than the total number of digits in Pi. 

From the TED-Ed Lesson The infinite life of pi - Reynaldo Lopes

Animation by Igor Coric