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Title
266
AskScience Panel of Scientists XVIII
634
AskScience AMA Series: IAmA restoration ecologist focused on restoring oysters to the NY Harbor in New York City. AMA!
9367
How does a master key work?
60
How is it so that several (all?) mammals grow and lose a set of "baby teeth" before growing their final dentition? Why stop at two sets when other vertebrates such as sharks regenerate their teeth constantly?
22
How do our eyes avoid being commonly infected through things like rubbing our eyes or the pollutants in the air?
22
If placed in a controlled environment, do trees that normally undergo seasonal leaf Abcission stop losing their leaves?
5522
How does sunscreen stop you from getting burnt?
6
Are women born with all their eggs?
16
Do nocturnal animals prefer sleeping conditions that are dimly lit or bright in contrast to humans which prefer dark conditions?
9
[Medicine] What leads a body to reject or accept donated organs?
33
If the human body has evolved over millions of years to swell up in response to an injury, why are we instructed to apply ice to prevent our evolutionary swelling response?
12
How do phones keep cool with small heatsinks and no fans?
7
How can we tell if someone we can’t see is shouting from far away or whispering close to us?
7
Why are shadows casted from objects more crisp depending on how far the object is from the ground?
12
How does a train engine, pulling miles of cars and many tons of load, get enough traction to actually move everything?
3
Would objects orbiting Earth, such as space debris, satellites, the ISS, be hot or cold to the touch?
18
Studies have shown that small movements in the throat occur during an internal dialogue--does that happen when music plays in your head, too?
5
What is causing this orbiting water droplet in my tea kettle?
2
How is hybrid fruit produced?
5
Why is cold weather usually synonymous with pneumonia infections?
6
Are there more cases of depression in modern times than in history?
65
Why does sunburnt skin feel hot to the touch?
10
Air molecules travel at 1000 mph. Can we harness that kinetic energy?
0
Are there any videos from NASA or other space agency where they do tests in the vacuum of space? Such as a plant or mice or anything is taken outside of the space shuttle/station
27
When you shake up a carbonated drink, where does the pressure go once it’s ‘settled’?
1
How is the mute/play next functionality on audio-jack earbuds implemented?
1
How does atmospheric scintillation work in detail?
10
In my chemistry class yesterday we learned about the pathlength of gas molecules in a gas at STP. What is the pathlength of interstellar hydrogen? What about the intergalactic medium?
6
Why is space and space travel illustrated, for the most part, on a horizontal line? Can't we space travel "upwards" or "downwards" and where would that eventually lead?
1
Can the exact solution of a system of non-linear equations be determined algebraically?
8
Is there any scientific evidence that dinosaurs roared (as seen in movies)?
3
Why don't we normally hear sounds when we move our heads?
0
Can rare astronomical phenomena such as solar eclipses or supernovas disrupt biological cycles of living organisms?
1
Angles allow you translate between X, Y and Z - is there an equivalent between time and the spatial dimensions?
15
How were the subduction zones discovered and observed?
22
What factors affect the orbit of our sun around the galaxy?
2
Which potassium compounds are present in lye water? If it's not KOH then how is it made from the ash?
6
Do mental illnesses run in families? Will they be the same mental illness or can they vary between each offspring?
5
Does the genetic composition of a woman's eggs change over her lifespan?
21
Why do images on a monitor become negtive when viewed from a certain angle?
14
How far in advance can we predict a major tectonic event?
2888
How are drugs like antidepressants (who’s effects aren’t immediately apparent) developed?
    Comments
39 hwillis Inflight WiFi is outsourced to a third party. Gogo is the most common by a lot. Getting WiFi up to an airplane is kind of tricky. Cell phone towers are specifically designed not to send signals upwards; that's why you lose your service so quickly. If cell phone towers sent signals upwards that power would basically just be wasted, so they don't. Most of the signal you *do* get is just reflected off the ground. That gets at the meat of why Gogo is expensive too- they have their OWN network of cellular towers. They operate on a similar frequency to normal cellphones, but only on the lowest band. There are a little over 200 towers in the US, compared to over 200,000 cell sites (towers + antennas mounted on buildings). There are [2-4 antennas](http://concourse.gogoair.com/gogo-atg-4-work/) on the underside of the plane that radiate omnidirectionally. The antennas feed a modem (or two) and get converted into WiFi signals inside the cabin. For transoceanic flights there are no towers. These flights use a separate antenna on top of the plane that talks to satellites- standard satellite internet on the Ku band. Gogo contracts out with a few companies for this, but the satellites are all relatively similar. they sit in geostationary orbit around 22,000 miles away. Omnidirectional antennas obviously aren't enough for this- you need to point a very good beam at these satellites to get a good connection. For context, that distance is roughly the circumference of the earth. The target is a bit bigger than the broad side of a barn. It's like if you stood in front of a barn, took aim, then turned 180 degrees and shot all the way around the planet and hit the *other* side of the barn. [These antennas](https://thepointsguy.com/wp-content/uploads/2015/10/antena.png) cost a *lot* of money. There are [a few](http://aviationweek.com/site-files/aviationweek.com/files/imagecache/medium_img/uploads/2017/05/gogo2ku-install.jpg) different [types](http://blog.wandr.me/wp-content/uploads/2014/07/IMG_8034_thumb.jpg) but they all seem to use phased arrays to some extent, with the newest versions moving entirely to phased array. Phased arrays are a little complex to explain but they let you aim the beam electronically instead of by physically turning the antenna. Eventually the cellular antennas will also use phased arrays (cell phone towers already do, to a very limited extent). Phased arrays are also the same kind of radar used in the biggest radar installations, early-warning missile launch systems. For instance Lt. Gen Trey Obering had this to say about [one such system](https://en.wikipedia.org/wiki/Sea-based_X-band_Radar): > The radar was described by Lt. Gen Trey Obering (former director of MDA) as being able to track an object the size of a baseball over San Francisco in California from Chesapeake Bay in Virginia, approximately 2,900 miles (4,700 km) away.
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    3. What allows certain cars and airplanes to have their own Wifi?
40 0 hwillis Inflight WiFi is outsourced to a third party. Gogo is the most common by a lot. Getting WiFi up to an airplane is kind of tricky. Cell phone towers are specifically designed not to send signals upwards; that's why you lose your service so quickly. If cell phone towers sent signals upwards that power would basically just be wasted, so they don't. Most of the signal you *do* get is just reflected off the ground. That gets at the meat of why Gogo is expensive too- they have their OWN network of cellular towers. They operate on a similar frequency to normal cellphones, but only on the lowest band. There are a little over 200 towers in the US, compared to over 200,000 cell sites (towers + antennas mounted on buildings). There are [2-4 antennas](http://concourse.gogoair.com/gogo-atg-4-work/) on the underside of the plane that radiate omnidirectionally. The antennas feed a modem (or two) and get converted into WiFi signals inside the cabin. For transoceanic flights there are no towers. These flights use a separate antenna on top of the plane that talks to satellites- standard satellite internet on the Ku band. Gogo contracts out with a few companies for this, but the satellites are all relatively similar. they sit in geostationary orbit around 22,000 miles away. Omnidirectional antennas obviously aren't enough for this- you need to point a very good beam at these satellites to get a good connection. For context, that distance is roughly the circumference of the earth. The target is a bit bigger than the broad side of a barn. It's like if you stood in front of a barn, took aim, then turned 180 degrees and shot all the way around the planet and hit the *other* side of the barn. [These antennas](https://thepointsguy.com/wp-content/uploads/2015/10/antena.png) cost a *lot* of money. There are [a few](http://aviationweek.com/site-files/aviationweek.com/files/imagecache/medium_img/uploads/2017/05/gogo2ku-install.jpg) different [types](http://blog.wandr.me/wp-content/uploads/2014/07/IMG_8034_thumb.jpg) but they all seem to use phased arrays to some extent, with the newest versions moving entirely to phased array. Phased arrays are a little complex to explain but they let you aim the beam electronically instead of by physically turning the antenna. Eventually the cellular antennas will also use phased arrays (cell phone towers already do, to a very limited extent). Phased arrays are also the same kind of radar used in the biggest radar installations, early-warning missile launch systems. For instance Lt. Gen Trey Obering had this to say about [one such system](https://en.wikipedia.org/wiki/Sea-based_X-band_Radar): > The radar was described by Lt. Gen Trey Obering (former director of MDA) as being able to track an object the size of a baseball over San Francisco in California from Chesapeake Bay in Virginia, approximately 2,900 miles (4,700 km) away.