31

Pluto was discovered by a manual search of the sky using a blink comparator. This is an extremely laborious process. For Pluto, it made sense to go to all this trouble, because there were indications that a ninth planet had to be out there: Neptune's orbit was perturbed by the gravity of another planet, it seemed. Later, it turned out that that wasn't the ...


31

There are a few special things about Pluto, as compared to the other dwarf planets in the Kuiper belt. These include: It is the largest dwarf planet known, by diameter. (Note, this was only determined after the New Horizon's flyby) It orbits relatively close to the Sun, at times it is even closer than Neptune! It has the largest satellite system of any non-...


28

With a resolution of 1E-09 radians, Jupiter would be 1 pixel wide at 7 light years. If you had 1E-10 radians, you could resolve the largest features. Visible light has a wavelength of 5E-07 meters, so if you wanted to use a cluster of telescopes to synthesize an aperture with some kind of coherent combination, "all you would need" is a 200 meter diameter ...


26

As stated, the answer to the question has to be yes, a telescope on the Moon can have significant advantages over a telescope on Earth, because of Earth's atmosphere. That's why we have space telescopes. However that is the wrong question. The real question is what advantages, as well as disadvantages, does a telescope on the Moon have over a telescope ...


26

Kepler has a parabolic dish antenna fixed to its body. There are many possible designs of transmitting devices. For spacecraft, parabolic dish antennas are preferred, because they have the least attenuation for radio waves with distance. But dish antennas must be pointed to the receiver. The Kepler telescope was over-budget for a Discovery-class mission, ...


20

The location of the North Pole is 21.18 RA, 52.89 North. There is no "North Star" located there, although it is about half-way between Deneb and Alderamin. (Source). In the sourthern sky, Kappa Velorum is a good South Pole Star. Here's also a few screenshots as to what the poles would look like: Mars North Pole: Mars South Pole: I've also added a bit of ...


17

If you can detect unusually large quantities (superabundance) of Xe-129 or higher isotopes of Xenon that would naturally only be present in trace amounts without explosions of thermonuclear weapons, then yes. Potentially even millions of years after the event (Xe-129 has a half-life of 16 million years). It is hard to estimate what weapon yield would be ...


15

Assuming best case? According to this page, about half the energy from a normal nuclear explosion is radiation. That means we can simplify it to all energy radiated for an order of magnitude estimate. For reference I will use the Tzar bomba, the largest nuclear weapon ever tested. It was about 50 megatons worth of TNT. According to unit conversion , a ...


14

This is the 1978 image of the Pluto system that led to the discovery of Charon. This is a negative, so the big black blob in the middle is Pluto and Charon. Charon? It's the little bump on the upper right of that blob. You can barely make out Charon. Additional satellites? No. This is a 1990 image of Pluto and Charon taken by the Hubble: This was before ...


12

The Hipparcos satellite was solely devoted to astrometry. It did not take 'regular' images, it used an eccentric Schmidt telescope to overlay images onto a grid. It finally resulted in a catalogue of stars, not an archive of images. It's purpose was to detect and find the position of stars in the sky. An 'image' taken by Hipparcos. As you can see, it's ...


11

As @Vedant Chandra says, Hipparcos was dedicated to astrometry. To do this properly, you need to make sure your measurements are accurate. The pointing accuracy of your satellite is a nice specification, but a system that does not rely on this can achieve more accurate measurements. To do this, Hipparcos looks in two directions at once. The telescope ...


11

Wolfram Alpha can do things like this easily, handling the units for you. Just entering "time to travel 1 AU at an acceleration of 25 g" gives the answer. The result is 9.7 hours. You can click on "Show formula" to see the formula used. It is one step beyond T=Distance/Velocity. That gets you up to 0.03 c (click "More units"), so relativistic effects ...


11

If my understanding in correct, the orbit is perfectly circular if the dimensionless orbital parameter of eccentricity (e) is zero. However, I'm not sure how the inclination works with this, and that comes down to the question "circular in what plane?" Anyway, I present to you: Asteroid 113474 (2002 ST57). http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=113474 ...


9

Because radio waves in space follow the inverse square law, it would require an exceptionally large antenna to pull in enough of an ordinary radio signal to actually notice it, let alone get any useful data. Consider that a typical radio signal is designed for distances measured in miles. TV broadcasts disappear into the noise within about 100 miles from ...


8

This is to do with Frames of Reference. The video below gets across nicely that all motion is relative, your perception of it depends on your point of view: Frames of Reference - Hume and Ivey, 1960, Educational Services Inc. If we chose the Sun as the center point of the Universe, we could say everything moves around it - ...


8

It is theoretically possible, but such a satellite would probably not be in a stable orbit. Such a system is not known in the Solar system and due to gravitational perturbations it would not last long. Popular Science Astro


8

To answer your original question regarding the state of affairs of space telescopes, from the US (NASA), besides JWST, there are two large space telescope projects. Work has started on the WFIRST (wide field infrared survey telescope). The LUVOIR (large ultraviolet/optical/infrared survey) telescope is in the study phase. WFIRST was originally a dark ...


8

2015 TB145 had an apparent magnitude of 20 when it was discovered. This is pretty faint and may account for it not being found earlier. Most asteroids have a small inclination (angle relative to the ecliptic plane). Some of the early asteroid surveys didn't look at high inclinations, because it can take a long time to do a survey of the entire sky. These ...


7

YES Ok, it is easy to say yes but the basic idea is statistics. There are more and more planets discovered outside of our solar system virtually every day. With better instruments, ever smaller planets can be discovered. Besides, it depends on your definition of 'earth-like'. If you restrict this to size, the distance to its star (with respect to the '...


7

Short answer - it's theoretically possible but extremely improbable. I found this very well referenced article explaining some of the challenges involved. Basically, we would need a REALLY huge receiver and we would need to know exactly where to point it. And we would need the extraordinary luck of pointing it during a time exactly like this one when a ...


7

Why would Kepler rotate towards Earth instead having an antenna always directed to Earth? There was no need to always have an antenna pointed directly at the Earth because communication with the Earth was infrequent, less than eight hours per month. There are a lot more deep space assets than there are receivers to communicate with those assets. The ...


6

Make the stationary center of your coordinate system the stationary center of mass of the two bodies (called the "barycenter"). Then by conservation of momentum, the total momentum of the system will always be zero. If the net momentum of the two bodies is not zero, then first subtract the velocity of their center of mass from both to make it stationary. ...


6

Asteroid 2010 TK7 is called an Earth Trojan. But it's orbit isn't as long lived as the Jupiter Trojans. According to Wikipedia: 2010 TK7's orbit has a chaotic character, making long-range predictions difficult. Prior to A.D. 500, it may have been oscillating about the L5 Lagrangian point (60 degrees behind Earth), before jumping to L4 via L3. Short-term ...


6

There are a few common misconceptions about the main belt's density and relative velocities between its members that seem to cause quite many of such questions similar to yours even on our site. This seems to boil down to how asteroid belt (aka main belt, because it isn't really the only asteroid belt in the Solar system) is often visually represented in ...


6

The answer is strongly defined by how one defines "Earth Like." The working definition has yet to be established for the scientific purposes that I've seen. The common minimum: terrestrial, within the liquid water zone, and not more than about 4 Earth masses; a lower bound of about 1/2000th Earth mass (large enough to be self rounding). In which case, ...


6

Martians could imagine a line formed by Deneb and Sadr, which have apparent magnitudes of 1.21–1.29 and 2.23 respectively (lower is brighter), compared with Polaris which varies between 1.86–2.13. This would get them a little less than 3° away from true north (compared to <0.5° for Polaris on Earth). They could also take the midpoint between Deneb and ...


6

No, Jupiter is simply too far away (Distance = less data transmitted), it's a hard environment (Lots of radiation), and relatively little is accomplished by sending it out so far. But I do know of at least one serious proposal to send a telescope to Mars. A bare bones spy satellite (Telescope only really) was donated to NASA, and a proposal called Mars ...


6

The Celestron telescope is not stationary. It can be moved around inside the space station to look through any window. It is however just used to observe the Earth, and the reason for that is the orbital velocity of the ISS. Moving at almost $8km/s$, the view change with an angular velocity of 3.88 arc-degrees per second because the station rotates to keep ...


6

The short answer: for optical astronomy (IR through gamma wavelengths), no, there isn't any huge advantage. But for radio astronomy there are distinct advantages to being on the lunar far side, they're just not related to any albedo differences. Electrostatic forces loft tiny (micron-sized) dust particles above the moon's surface. When lit by sunlight they ...


6

As @uhoh has pointed out, optical interferometers only a little bigger than the ones we have now would allow imaging of large-scale features of large planets around nearby stars. For a more detailed view of smaller or more distant planets we either need much larger interferometers (the optical equivalent of VLBI techniques used for radio) or to use ...


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