When You Turn Off A Light, Where Does The Light Go?

In space, light will go on, and on, and on… In a windowless room, where does the light go when we switch it off?

Light is a pretty simple beast. In lieu of any interference, it will go on, and on, and on, as we see it doing in the vast (mostly) empty realms of interstellar & intergalactic space.

Space is a rather unique case, because in between massive objects, light is travelling through something very close to a pure vacuum...

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What Does The Sun Sound Like?

What sound does the Sun make, and would it be musical if we could hear it?
This montage of 366 images shows our Sun through the eyes of ESA’s Proba-2 satellite, as seen each day in 2016. The satellite’s SWAP camera works at extreme ultraviolet wavelengths to capture the hot turbulent atmosphere of the Sun, known as the solar corona. Each image was created from 30 separate images centred on 01:00 GMT each day, which were processed to enhance the features extending from the solar disc. Throughout 2016 the Sun’s 11 year activity cycle continued towards its minimum, a period when the number of sunspots, active regions, solar flares and eruptions diminish. Nonetheless, the most active region of last year can be seen in the 17 July image. The bright region close to the centre of the Sun produced eight of the 20 most powerful flares witnessed last year. Other prominent features are coronal holes – darker regions indicating lower levels of emission. However, coronal holes can produce streams of fast solar wind that can trigger geomagnetic storms on Earth. One of the largest holes observed last year can be seen towards the north of the Sun on 24 November, and was present for several solar rotations. Image credit: ESA/Royal Observatory of Belgium

This montage of 366 images shows our Sun through the eyes of ESA’s Proba-2 satellite, as seen each day in 2016. The satellite’s SWAP camera works at extreme ultraviolet wavelengths to capture the hot turbulent atmosphere of the Sun, known as the solar corona. Each image was created from 30 separate images centred on 01:00 GMT each day, which were processed to enhance the features extending from the solar disc. Throughout 2016 the Sun’s 11 year activity cycle continued towards its minimum, a period when the number of sunspots, active regions, solar flares and eruptions diminish. Nonetheless, the most active region of last year can be seen in the 17 July image. The bright region close to the centre of the Sun produced eight of the 20 most powerful flares witnessed last year. Other prominent features are coronal holes – darker regions indicating lower levels of emission. However, coronal holes can produce streams of fast solar wind that can trigger geomagnetic storms on Earth. One of the largest holes observed last year can be seen towards the north of the Sun on 24 November, and was present for several solar rotations. Image credit: ESA/Royal Observatory of Belgium

Sound is a tricky thing in space. Sound is a pressure wave, an oscillation in the density of air or water, which moves through the air or through water until it reaches something it can rattle. If that sound is reaching a human ear, and if the oscillation is within the range of frequencies we are sensitive to...

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Is There Any Way To Slow Down A Solar Sail?

I recently read an article about a project called Breakthrough Starshot. It’s been proposed to send a tiny craft to Alpha Centauri at 20% the speed of light and the craft(s) would arrive in 20 years or so. Let’s say that there’s been a successful launch and the tiny ship is on it’s way. Would Alpha Centauri have enough gravitational pull to capture an object moving that fast or would it be a one time fly by like New Horizons and Pluto?
This image shows the closest stellar system to the Sun, the bright double star Alpha Centauri AB and its distant and faint companion Proxima Centauri. In late 2016 ESO signed an agreement with the Breakthrough Initiatives to adapt the VLT instrumentation to conduct a search for planets in the Alpha Centauri system. Such planets could be the targets for an eventual launch of miniature space probes by the Breakthrough Starshot Initiative. Image Credit: ESO/B. Tafreshi (twanight.org)/Digitized Sky Survey 2 Acknowledgement: Davide De Martin/Mahdi Zamani

This image shows the closest stellar system to the Sun, the bright double star Alpha Centauri AB and its distant and faint companion Proxima Centauri. In late 2016 ESO signed an agreement with the Breakthrough Initiatives to adapt the VLT instrumentation to conduct a search for planets in the Alpha Centauri system. Such planets could be the targets for an eventual launch of miniature space probes by the Breakthrough Starshot Initiative. Image Credit: ESO/B. Tafreshi (twanight.org)/Digitized Sky Survey 2 Acknowledgement: Davide De Martin/Mahdi Zamani

You’ve got a pretty good handle on Breakthrough Starshot - their goal is indeed to ship off a tiny little craft, attached to a huge solar sail, and use high powered lasers to accelerate the craft to a speed much faster than what the power of the sun could do alone.

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Would You Float At The Core Of The Earth?

Thought experiment...if you built a bedroom sized room at the center of the Earth, and you are in that room, which way is down? Please explain to me why if you are surrounded by the same amount of mass in every direction, how does that NOT EQUAL NET ZERO? In other words, would that not be the exact same thing as weightlessness? So what would an illustration of the curvature of Space look like at the center of a massive body? Wouldn’t there be a vortex of some sort? It’s kind of important to me to understand where I’m going wrong?
A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. The NPP satellite was renamed 'Suomi NPP' on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin. Image Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. The NPP satellite was renamed 'Suomi NPP' on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin. Image Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

You very nearly got there! Let’s run with your example of a small room at the center of the Earth, but for my sanity, I’m going to make your room a sphere instead of a square, because everything else involved in this example is going to be round...

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How Long Until The Moon Slows The Earth To A 25 Hour Day?

At this rate of the Moon’s gravitational force slowing down Earth’s rotation, how long will it take to increase an hour to our day?
NASA's Lunar Reconnaissance Orbiter (LRO) recently captured a unique view of Earth from the spacecraft's vantage point in orbit around the moon. Image Credit: NASA/Goddard/Arizona State University

NASA's Lunar Reconnaissance Orbiter (LRO) recently captured a unique view of Earth from the spacecraft's vantage point in orbit around the moon. Image Credit: NASA/Goddard/Arizona State University

The Earth’s rotation is indeed being slowed down by the presence of the Moon - every year, the Moon gains a little energy from the Earth, and drifts a little farther away from us. This drift is imperceptible to the human eye, but measurable...

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