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97

The border between India and Pakistan is one of the most heavily guarded and well-lit borders in the world, so much so that it can be seen from space at night. It covers an immense distance from the Arabian Sea to the Himalayan foothills. Here is how it looks from ISS. India-Pakistan Border at Night from NASA Earth Observatory The winding border between ...


82

You're observing shamefully bad journalism. The "protect Earth from aliens" bullet point in the "Highlights" section of the article was put there by an editor who either ignorantly or willfully distorted the actual role of the Planetary Protection Officer. The first paragraph of the story gets a little closer: The full-time role of "planetary ...


72

In your simulation, the camera (or the viewers perspective) is stationary in what seems like in an altitude of a geostationary orbit. However the ISS is not stationary, it is travelling 7.6 km/s. It completes one orbit in 92 minutes. The ISS orbiting is giving the illusion that the Earth is spinning that fast. Note: The Earth does still spin while the ISS ...


44

No; the first full views of Earth from high-altitude satellites predate Apollo 8 by at least two years. This web page has a nice progression of pictures of Earth from space from 1959 on. A Soviet satellite (possibly Molniya-1-3) took this crude picture on May 30, 1966: DODGE took this picture in September of 1967; this is believed to be the first full-...


40

I treated this as a problem of geometry and came up with this: The sun is the large yellow disk. The earth is the largest black disk, obscuring most of the sun The left-hand dark-grey disk is the moon as it transits across the near-side of the earth, with respect to L2. In reality in this position, the disk of the moon would appear completely black. I ...


35

The simple answer is yes. The more complicated answer starts to look at types of orbit. You could have a figure-8 orbit, which has centres around both. You could have an orbit that goes around the centre of mass of the two bodies (in the case of Earth - Moon this is a point within the Earth, but for Pluto-Charon it lies between the two bodies) - this is ...


33

It isn't the actual level of charge (potential) that causes electric shock. but being connected to two things (like your iron and the ground) that are at different levels. Hence why birds can sit on a 750kV overhead line and not fry. The earth wire in a domestic system exists to keep all exposed metal at the same potential. Grounding everything to the frame ...


31

You're right: this has issues. You can insert a station into a circular orbit halfway between Earth and Mars, but because this has an orbital period also in between those of Earth and Mars, your station won't be in a usable position most of the time. So you'd have to fill the orbit with several station to always have one reasonably close. The fuel is also ...


26

Initial and Bonus Answer: With a volume of 609.31 M^3 and an empty mass of 15,500kg (13,500 kg empty weight plus 2,000kg for the attached Instrument Unit), J002E3 is Apollo 12's S-IVB stage (designated S-IVB-507). It was intended to be placed in a heliocentric orbit following Apollo 12's TLI Burn. Due to insufficient propellant, however, it ended up ...


23

The spacecraft that orbit at L2 usually don't just stay at the L2 point, but do what's called a Halo Orbit, or related Lissajous Orbit. Essentially they orbit the L2 point, instead of right at it. As a result, they actually see the Earth and Moon as distinct from the Sun. And they usually orbit the point in such a way that they will not have a direct line ...


22

http://en.wikipedia.org/wiki/Lagrangian_point A satellite orbiting at the L1 point or L2 point would be in constant contact with the moon. Unfortunately, neither of these are particularly useful for keeping in contact with a lunar mission. The L1 point is between the earth and the moon, and would offer no advantages over just putting the reciever on earth....


22

As others have noted, the ISS orbits the earth extraordinarily quickly, and that explains the discrepancy. However, there may still be a small error in your simulation. Whether or not there is an error depends on where you intend the "camera" to be. My suspicion is that your simulation was created as follows: Make a sphere at the origin, inclined 23 ...


22

I would say it's probably Envisat. It is definitely the heaviest although i'm not sure if it is also the largest piece volumetrically. We had a full scale 'mock up' at our faculty and I can confirm that it is absolutely massive! They have been thinking about ways to deorbit it for quite a while now since a collision involving this large of a satellite could ...


21

Although not a blue marble as it's in black and white, Lunar Orbiter 1 took an earlier Earthrise photo on August 23, 1966. This is the first picture of the Earth from Lunar orbit. In 2008, the Lunar Orbiter Image Recovery Project produced a higher-quality version of this image by reanalyzing the original data. Lunar Orbiter 1 also took a second Earthrise ...


19

"Earth" doesn't work the way you might think. In any case, on a vehicle of almost any kind, "earth" is replaced by "metal chassis". Your question is based on a very common misconception: that electricity wants to return to earth. Actually, electricity wants to return to source. For instance, electrons at a battery's negative terminal want to return to ...


18

As you mention, the horizon seen at ground level will appear as a plan taking up 180° of our field of view. This is known as the astronomical or sensible horizon. As soon as the observer gains altitude the horizon line moves below the observer horizontal plan, by an angle called dip angle. The separation between the Earth and the sky now appears under an ...


18

If I understand your edited question, then no. While the Earth's J2 (oblateness) produces enough torque to rotate a Sun-synchronous orbit once a year, it does not produce enough torque to rotate a "Moon-synchronous orbit" once a month. So there is no such orbit. I am not clear on what the utility of such an orbit would be, even if it did exist. If you're ...


17

Another border which is visible due to the lack of light is the Haitian border with the Dominican Republic: The area highlighted on the left is Haiti, of which only Port Au Prince can be seen at night. The bright island on the right is Puerto Rico.


16

One of your instincts was correct; it is indeed the influence of the Moon. Wikipedia notes: Over millions of years, the rotation is significantly slowed by gravitational interactions with the Moon; both rotational energy and angular momentum are being slowly transferred to the Moon: see tidal acceleration. And here is the general case of a satellite ...


15

You did not specify if you are thinking of any border or only an anthropogenic one. Anthropogenic (they will likely be visible due to different levels of economic development): Egypt and Israel (different level of development visible on both sides) Haiti and Dominican Republic (less vegetation in Haiti) Natural ones (rivers and mountain ranges can be seen ...


14

There is a chamber at the German Aerospace Center designed to imitate the Martian environment. So far there are two published experiments showing that some organisms could survive in the chamber. An imitation of Martian regolith was used, and the organisms were exposed to an imitation of Martian atmosphere with the pressure, temperature range, moisture ...


13

It is possible in several ways. Let's get the dumb ones out the way first. As I commented, you can orbit the moon itself. Technically correct, since anything orbiting the moon is also orbiting the Earth. You can make your satellite big enough so that it always has a line-of-sight. A giant pole somewhat longer than the Earth's diameter can be arranged to ...


13

At any latitude, the Earth completes one rotation per day. At the equator, the circumference of the Earth is about 40000 km, so the speed of rotation is 40000 km/day or 463 m/s. If you pick a line of higher latitude and look at it on a globe, you will see that the line of latitude is smaller than the equator. One rotation completed in a day is therefore ...


13

Surprisingly, yes, for some of them. Small, old stars can be at room temperature ex: WISE 1828+2650, so you could touch the surface without getting burned. Any star you can see in the sky with the naked eye, however, would be hot enough to destroy your body instantaneously if you came anywhere near them. An article about cold stars: https://www....


13

The planetary protection officer has 2 major functions: Protect other planets from contamination by our space probes Protect the Earth from contamination by alien matter The press have for some reason sensationalized this. Alien matter in this case does not mean little green men with laser pistols, it means matter from any celestial body or object other ...


13

While LED lighting is taking over (and is likely CW), plenty of outdoor street lights in cities and highways still use high pressure mercury and sodium discharge lamps running on mains AC voltage. They don't rectify and so will produce two pulses per cycle of AC. Therefore any technique that can chop up time, a rolling shutter effect or simple aliasing in ...


13

The ISS takes approximately 90 minutes to circle the Earth. This presumably results in the higher apparent speed of rotation.


13

Answer for Bonus question Not entirely sure if indeed the biggest (in heliocentric orbit), but bigger than roadster for sure: S-IVB, the third stage of Saturn V rocket that was used for Apollo lunar missions (height 17.81m, diameter 6.6m) https://en.wikipedia.org/wiki/S-IVB There are few of them in heliocentric orbit. https://en.wikipedia.org/wiki/...


12

Because, first, we will never fix everything. Humans are always naturally dissatisfied with their state of affairs, no matter what those are. Reference "first world problems" (see image). Compared to how things were hundreds of years ago, we have already solved all of the problems of that time and are now at what would have been to them an unimaginable ...


12

Mars cyclers have already been mentioned in the comments, with the Aldrin cycler being one example of them. The castle parts of them could be seen as ferries, and the visiting taxis as means of embarking and disembarking during visits of planets along their routes. And three or more bodies cyclers are also possible, for example the so-called resonant ...


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