78

The reason there are so few spacecraft placed at Lagrange points is that it's much harder to get there. Launching sizeable payloads to Earth escape velocities requires a very large vehicle and is simply impractical/impossible for many missions. For example, at the time of its launch, there was no launch vehicle in operation capable of lifting Hubble's 11000 ...


41

Yes, I've done it myself in my backyard in suburban Houston. During a spacewalk in ISS increment 50, an MMOD shield intended for the axial port of Node 3 was lost. It's visible in this video floating below station. It ended up reentering about six months later. A few weeks after it had been lost, I noticed that it would be visible from my house, with a ...


40

There are a few positional lights on the visiting spacecraft to the International Space Station (ISS), also doubling as indicators that the visiting spacecraft docked to the station are powered and similar reasons. And the Canadarm2 has lights on it so it can be remotely / CCTV operated also when the station is in the Earth's shadow, and they do have lights ...


40

It's not a powered light; what you're seeing is sunlight reflected from the solar panels. That's why you can only see it during near overhead passes around dusk and dawn - the sun has not yet "set" from the space station's altitude. From http://nasa.gov/vision/space/travelinginspace/f_skywatch.html The Space Station is one of the most visible man made ...


34

Yes, it's perfectly possible to observe the International Space Station with a naked eye from most latitudes, unless you're observing from one of the two polar regions, in which case the angle at which it would be visible would likely be too low on the horizon and blocked by local topography. From one of my answers on Astronomy.SE: Two basic conditions need ...


28

Yes, you can. When it is illuminated by the sun, it is brighter than any star and moves with a quite high speed across the night sky which makes it quite easy to spot. Because of its low orbit it can only be seen from a small area at any given time, but thanks to its strongly inclined orbit it regularly passes over most inhabited areas of earth. You can ...


28

You can find the image on Flickr. On August 31, 2012 a long filament of solar material that had been hovering in the sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The coronal mass ejection, or CME, traveled at over 900 miles per second. The CME did not travel directly toward Earth, but did connect with Earth's magnetic ...


26

Hubble can in fact observe the Moon, and has done so. Here's a picture of the Apollo 17 site (The upper right is from Apollo 17 mission itself). The x shows where the actual site is. You can also see more Hubble pictures of the Moon at this page.


24

As several nations' governments and plenty of amateurs pointed radio frequency antennas at the sites and received signals, one might conclude that they were observed. Observation does not have to imply visible light observation. See this http://www.arrl.org/eavesdropping-on-apollo-11 My recollection from the time is that plenty of amateurs tuned in to the ...


24

Short answer No it hasn't been possible to see what was happening on the Moon, from Earth. The angular size of an object like the Lunar Module is much much smaller than the best angular resolution available in 1969. To imagine what happens when the resolution of the telescope is not sufficient, let's observe a strip of black and white lines with ...


23

Having observed the International Space Station numerous times passing over the early night skies, on a clear night and when my eyes are rested (I stare a lot at monitors like I'd guess most of us here) having normal visual acuity (20/20 vision), I can assure you that your friend's claims are quite impossible even for an experienced amateur astronomer with ...


21

No they were not. Telescopes, even today cannot resolve that small a detail from the distance. LCROSS, orbiting the moon was able to barely resolve the lunar modules left behind. More good details in this similar question and answer on the Astronomy site: Visibility of the Apollo-11 Module


19

To be visible from the ground, a satellite (including the ISS) must satisfy several conditions: It must be above the horizon It must be illuminated by the sun The observer's sky must be sufficiently dark to not overwhelm the reflected light from the satellite. Those three conditions basically mean that with the exception of a few extremely bright Iridium ...


18

An object of that size would be detected almost instantly on first pass by the United States Strategic Command, which sweeps Earth's Sphere Of Influence to track and catalog objects that are in Earth orbit. Radar picks up most objects which are close and reasonably large. Anything greater than a metre in diameter can be tracked with relative ease, in fact, ...


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

First, let's clear the part about how far away Kwangmyongsong 4 (KMS-4, NORAD ID 41332) is. It was inserted into a 472.6 km × 508.5 km near-polar sun-synchronous orbit with inclination of 97.5°. It is not geosynchronous, so its orbit takes it over all the longitudes of the globe, and latitudes of 80.5° North to 80.5° South. That means that roughly once per ...


17

Here's a geometric construct to back up @uhoh's answer. Start with a satellite in orbit about earth (radius $R$) at height $h$. The inner circle is the surface, outer is the orbit. Each blue wedge is swept out in equal time by the satellite. Each gold wedge is shows how far you, an observer on the surface, sees it move in that same time. Blowing it up a ...


16

Progress-M 27M was (on date of writing this answer, see updates below) expected to decay around Thursday, May 7, 2015 at 23:01:00 ±8 hours UTC. This predicted reentry time will get more precise as it experiences atmospheric decay, additional radar tracking measurements are taken and object's TLE are updated. Eventually, it should be possible to predict ...


16

To add to the existing good answer about the practicalities of launching to Lagrange points, it's also worth considering why the missions which have gone that far are using the unstable Lagrange points, when L4 and L5 are stable. It comes down to what happens if the satellite loses control. In unstable Lagrange points, if the satellite gets fried somehow ...


15

If memory serves correctly*, then the angular diameter of the Sun as it appears on the skies of Mercury from its surface is larger than its total angular displacement during its apparent retrograde motion at Mercury's perihelion. So assuming that's correct and my memory didn't suffer too much in the 80's, the disco ball, erm, the Sun won't set anywhere on ...


14

Yes, you can see the ISS with the naked eye under certain conditions. As for identifying it, it will be quite bright compared to stars and it will be visibly moving. It will not have flashing anti-collision lights like a plane. It will be a more-or-less constant intensity bright light and will appear to be moving across the sky faster than a cruising jet ...


14

No, and the reason is simple enough. GEO is at an altitude of 35,786 kilometres (22,236 mi) above the Earth's equator and no satellites in geostationary or geosynchronous (GSO) orbit are large enough to reflect sufficient amounts of light towards the observer with their truss and solar panels to be visible to the naked eye on the surface of the Earth. They'...


14

Well, we can't observe it with the Hubble telescope. It's just too small. From astroengine.com Using the equation: $(d / D) × c = φ$ where $d$ is the diameter of the Oort Cloud comet (some estimates put this number at an upper limit of 300 km for the diameter of a cometary nucleus), $D$ is the distance from the Oort Cloud to Hubble (0.3 light years, ...


14

Introduction to selecting a reference surface The surface of any celestial body can be anything but uniform. The oceans, where existing, can be treated as reasonably uniform, but the surface or topography of the land masses can exhibit large vertical variations between mountains and valleys. These variations make it impossible to approximate the shape of ...


14

The latest measurements used by JPL Horizons to calculate its trajectory were reported on 3/27 as follows: 2018-Mar-27: Two reporting sites (J94 & K93) extend data arc one month. That is the last update that is included on the site, and thus seems likely to be the last update. Looking at the two mentioned observatories, neither of them has a public ...


13

Disclaimer These are from my own personal experience, which only encompasses launches from the east coast of Florida. Other US launch sites include Vandenberg AFB in California, which does have some decent viewing sites (though I do not know details), and Wallops Island, Virginia (about which I know next to nothing). I also have no real knowledge ...


13

The United States Space Surveillance Network has 20 sites around the world, and satellites as well, dedicated to detecting and monitoring objects near Earth. The European Space Agency also operates installations that monitor near-Earth space, full-time or part-time, in Germany, Norway, and Spain. I couldn't find public information on Russia's network. ...


13

The RSC Energia has recently published a study on the effect of high-velocity impacts of meteoroids and space debris on glass windows of the ISS in their "Kosmicheskaya Tekhnika i Tekhnologia" quarterly journal. At page 55 they have a nice three view scheme of Zvezda windows locations with the sizes, directions and angles specified: Figure 1. ...


13

Getting hard numbers about how accurate measures we can get from current systems, adapted to the Sun instead of far away stars is difficult, bordering to impossible. But we can get data about the relative difficulty of the solar system planets. First off, we can do some cheating for Mercury and Venus, as they occasionally go in front of the Sun. Given your ...


13

I'm posting these images as a supplement @Hobbes's accepted answer and @TildalWave's comments (which includes links to these images). I started reading some of those links. The gallery is a good starting place but there are different tabs to check out. The values 171 and 304 represent the central wavelengths used, in Angstrom units. Our visible spectrum is ...


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