cornucopiaofmadness asked:

Why can radio and microwaves travel through space but sound can't?

Because sound waves are vibrational waves, while radio and microwaves are electromagnetic in nature.

Sound waves require a certain density of matter in order to travel and vibrate through. That’s why sound works on earth, but that doesn’t in space. There is an abundance of free molecules to vibrate through (molecules in the air). That’s how sound works by vibrating atoms and molecules.

But in space there are so little molecules available that sound waves cannot propagate.

Why electromagnetic waves can travel through space or a vacuum is more complicated and is a bit beyond my knowledge. But the gist of it is that, its because of wave particle duality and the fact that the particle involved is a photon. And photons do not require a medium to travel through.

If any physics people can elaborate or correct me, feel free.

Planetary Nebula Mz3: The Ant Nebula

Why isn’t this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round.   Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round?   Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star visible above at the nebula’s center. One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star. A competing hypothesis holds that the central star’s own spin and magnetic field are channeling the gas. Since the central star appears to be so similar to our own Sun, astronomers hope that increased understanding of the history of this giant space ant can provide useful insight into the likely future of our own Sun and Earth.

Image Credit: R. Sahai (JPL) et al.,Hubble Heritage Team, ESA, NASA

Artificial Gravity

Did you know it’s a thing?

Did you know there are artificial gravity chambers at carnivals?

When I was a kid there was a ride at the local theme park called the “Turkish Twist” where a bunch of people get into a circular room. The room then starts spinning.

As the spinning gets faster, you’re increasingly pressed back into the wall with more force. Once you’re essentially sticking to the wall, the floor drops away but you stay, stuck to the wall.

Since there are health issues with being in a 0 gravity environment, NASA decided to try their hand at a similar form of artificial gravity:

Gemini 11, while in orbit, tethered itself to another spacecraft and they fired their thrusters sideways, creating one giant spinning spacecraft connected in the middle by a big tether (shown above).

It worked, NASA had created a whopping 0.00015 g (which isn’t much - Earth’s surface there’s 9.81 m/s^2). The important thing is that we now know artificial gravity works in space. The technical term for this is centrifugal force

There’s (of course) a problem. The amount of speed you’d need to spin at to generate anything useful in a spacecraft as big as Gemini 11, or even the International Space Station, would be so great that the blood would have trouble circulating to your head (it would be forced to your feet by the spinning).

The size of a spacecraft required to safely generate artificial gravity is at least the size of a football field, so until we’re able to lift such structures into orbit (or build them in orbit), we’re probably not going to see use of physics to mimic gravity. Who knows what the future holds though?

(Image credit: NASA)

3

Solar Flares and CME’s: Coronal Mass Ejections 

A Solar Flare is a sudden flash of brightness observed over the Sun’s surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy. They are often, but not always, followed by a colossal coronal mass ejection. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event. The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies.

A Coronal Mass Ejection (CME) is a massive burst of gas and magnetic field arising from the solar corona and being released into the solar wind, as observed in a coronagraph. Coronal mass ejections are often associated with other forms of solar activity, most notably solar flares or filament eruptions, but a broadly accepted theoretical understanding of these relationships has not been established. 

CMEs most often originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days.

Giffed by: rudescience  From: This video by nasa

An ancient globule

This image captures the stunning NGC 6535, a globular cluster 22 000 light-years away in the constellation of Serpens (The Serpent) that measures one light-year across.

NGC 6535 was first discovered in 1852 by English astronomer John Russell Hind. The cluster would have appeared to Hind as a small, faint smudge through his telescope. Now, over 160 years later, instruments like the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) on the NASA/ESA Hubble Space Telescope allow us to capture the cluster close up and marvel at its contents in detail.

Credit: ESA/Hubble & NASA
Acknowledgement: Gilles Chapdelaine
Source: http://www.spacetelescope.org/images/potw1452a/