Tag Archives: Education

Retrograde Orbits

(note: This animation has no audio track.) – The Open University

Although many moons in the Solar System follow prograde orbits, there are some notable exceptions. The gas giant planets Jupiter, Saturn, Uranus and Neptune have several small outer moons that follow retrograde orbits; this means that they orbit their planet in the opposite direction to the planet’s rotation. In a retrograde orbit, a moon revolves in its orbit in the opposite direction from that in which the planet rotates about its axis.

Video by The Open University.

More information at https://www.futurelearn.com

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Solving the Assessment Puzzle — Open Matters

By Sarah Hansen, OCW Educator Project Manager Assessing students’ learning is one of the most important things we do as educators. It’s also one of the most complicated. There’s a lot to consider: When will assessment happen? (Along the way? At the end of the course?) How will we collect useful information about student learning? […]

via Solving the Assessment Puzzle — Open Matters

A Brief History of the Universe

The universe is the biggest and oldest thing we know. It contains all existing matter and space. And its origin marks the beginning of time as far as we understand it. We don’t know what made the formation of the universe possible, nor why it occurred. The visible universe is currently about 93 billion light years wide.

A light-year is a distance that light travels in a year, which makes the universe about 880 trillion trillion metres wide. The visible universe is, however, still expanding, and we can measure that rate of expansion. Then, working backwards, we can figure out when the universe would have begun. To the best of our knowledge, the universe formed about 13.8 billion years ago in what is commonly referred to as the Big Bang.

This image shows the universe about 370000 years after the Big Bang, which is the oldest light that we’ve been able to record with the greatest precision. The image records ancient light or cosmic microwave background. The colours show tiny temperature fluctuations from an average temperature. These indicate areas of different densities, which became the stars and galaxies of today. Red spots are a bit hotter and blue spots a bit cooler. The image was recorded between 2009 and 2013, during the Planck mission, when the space observatory was operated by the European Space Agency, in conjunction with NASA, the National Aeronautics and Space Administration. Today, the universe is very cold. On average, it is 2.7Kelvin. Kelvin is a measure of temperature with the same magnitude as degrees Celsius. But 0 Kelvin equals minus 273.15 degrees Celsius.

In the universe, the hot parts, such as stars, make up only a tiny fraction. If we wind the clock backwards, the universe gets smaller. And this means the universe was hotter in the past. When matter gets hot, solids melt and liquids boil. The hot matter glows – red at first, but it becomes bluer as the temperature goes up. Eventually, all matter is gas. So we have a bright, glowing blob of gas. Going further back in time, as the gas gets hotter, the electrons are separated from the nuclei and a plasma is made. The temperature at this point is about 3000 to 6000 Kelvin and the glowing blob is white hot. As we go back further in time, the universe gets even smaller and hotter.

The nuclei themselves, containing protons and neutrons, are broken up. The reason for the breakup of nuclei is that the individual particles and the energy of the radiation are so great that the collisions of all this hot stuff are incredibly violent. The light is no longer in the visible spectrum. It is energetic enough to be x-rays and even gamma rays. Between just 10 seconds and 1000 seconds after the Big Bang, subatomic particles, including neutrons and protons, were formed. Neutrons live for just 9 minutes when they are free. Hence only those that stuck to protons during this period survived. All of the ordinary matter present today formed in this short window of time.

At about 1 microsecond after the Big Bang, the universe was very hot, at 10 to the 10 Kelvin, and quarks formed stable particles called hadrons. Before 1 picosecond, or 10 to the minus 12 seconds, the universe was an exotic place. The gas was hotter still and the laws of physics appeared different to how we see them today. The distinction between matter and radiation, such as light, cannot be detected. The forces of electromagnetism and the weak nuclear force also become indistinguishable. At the very earliest times, the universe was so hot and dense that we cannot yet describe them accurately.

Source Reference:
https://wmap.gsfc.nasa.gov/universe/bb_cosmo_fluct.html
http://www.evolutionpages.com/big_bang_no_myth.htm

My Blog:
https://thegeekiestone.com/

Insights on Teaching Japanese, in Japanese (and English) — Open Matters

By Joe Pickett, OCW Publication Director OCW has just published 21G.503 Japanese III, the third in a four-course sequence on Japanese taught at MIT. With relatively few Japanese speakers on the MIT campus, the instructors must make the most of what happens in the classroom and motivate students to work hard outside it. The course […]

via Insights on Teaching Japanese, in Japanese (and English) — Open Matters

Why Alien Life Would be our Doom – The Great Filter

New video by Kurzgesagt – In a Nutshell. Sharing this as it’s very interesting for all to know 🙂

 

The first 688 people to use this link will get 20% off their annual membership: http://brilliant.org/nutshell

Finding alien life on a distant planet would be amazing news – or would it? If we are not the only intelligent life in the universe, this probably means our days are numbered and doom is certain.

Kurzgesagt Newsletter: http://eepurl.com/cRUQxz

Support them on Patreon so they can make more videos (and get cool stuff in return): https://www.patreon.com/Kurzgesagt?ty=h

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The MUSIC of the video:

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