Arne
  • Member for 8 years, 4 months
  • Last seen more than 3 years ago
How powerful a telescope would allow me to view the astronauts aboard ISS do a space-walk?
24 votes

Ralf Vandebergh is one of the best amateur astronomy photographers out there who does spacecraft photography. He is using a 10" (25.4cm) Newtonian telescope, as far as I know, so this is pretty much ...

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Why does Titan's atmosphere not start to burn?
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16 votes

Titan is one of Saturn's moons. Titan has a dense atmosphere, at about 1.5 bars. It also seems to have lakes of liquid methane. For a conventional combustion, you would need a good Methane-Oxygen mix....

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Will Neptune be visible with the naked eye if I am standing on its satellite
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15 votes

NASA's Neptune fact sheet states that Neptune's irradiance is $1.51 W/m^2$. This is roughly three orders of magnitude less than at Earth (at $1367.6 W/m^2$). This sounds like a lot, and it is quite an ...

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Should I focus more on Aperture or Focal Length for a telescope?
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14 votes

There is one rule that is generally true for all deep sky objects (nebulae, stars, galaxies,...): Aperture matters! For solar system objects, aperture is not that important. The second most ...

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Moon orbits crossing each other
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14 votes

There is one known pair of moons in the solar system that seemingly swap orbits every couple of years. That's Saturn's Epimetheus and Janus. Their orbits are so close together that they interact ...

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Could someone explain RA/dec in simple terms?
14 votes

The equatorial coordinate system is very similar to the system used on a globe or on maps. To specify a point on a sphere or a globe you need only two numbers. These are the longitudes and latitudes. ...

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How Does a Refractor Telescope Work?
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11 votes

All telescopes have in common that they gather and focus light from far away objects. They use a primary opical element, such as a concave mirror or a (planar- or bi-)convex lense (or lense system), ...

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Why did the Comet Shoemaker-Levy-9 fragments cause such large explosions on Jupiter?
10 votes

Shoemaker Levy 9 was estimated to have released kinetic energy equivalent to 300 gigatons of TNT. That is $1.255 \times 10^{21} {\rm J}$. This release through friction and compression was sufficient ...

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What limits the usable focal length of telescopes currently?
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7 votes

Visual resolution of a telescope is directly proportional to the aperture of the telescope. The focal length, and hence the magnification that can be achieved, is then just following on the visual ...

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Jupiter FM - What are practical and inexpensive ways for the amateur detection of signals from Jupiter, especially of the transit of her moons?
7 votes

The StarGazers lounge featured a radio kit article for Jupiter radio astronomy. The same article is also featured over at the Radio Group of BritAstro. It seems that 20.1 MHz is the suitable ...

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Affordable night sky photography
7 votes

For long exposure pictures you need to have a motorized mount for your camera. The earth's rotation will lead to streaks otherwise. An affordable way to do this is to use a standard tripod with a star ...

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Gallery of 'actual images' from space?
6 votes

You can use one of the digital sky surveys. Examples include: Sloan digital sky survey SDSS ESO online digitized sky survey Their images contain visible (red or blue) wavelengths as well as infrared....

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How does the Milky Way look like above 66° North and below 66° South?
5 votes

On midnight, right around this time of year, the Milky Way will be in the zenith. Here is an XEphem rendering for the north of finland (65th latitude) for yesterday midnight (the brown outline marks ...

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What can be seen with a 4.5" telescope
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5 votes

The aperture of your 4.5" telescope is one thing, it's also important what focal length you have. Is it a f/5 or rather a f/8? The f/8 would be suitable for viewing the Moon, Jupiter, Saturn, maybe ...

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What's the largest non-spherical astronomical object in the universe?
5 votes

If you count conglomerates of galaxy style objects, the largest structure in the universe so far is the Huge Large Quasar Group. It seems to be four billion ly in size, and contains dozens of Quasars,...

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How would light from a blue or red star affect the way we see?
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4 votes

I guess it would be influenced. Right now, our vision is already influenced by that massive blue sky above us. The human visual system corresponds to the large influx of blue light that gets scattered ...

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What are some night sky objects I could see with my Celestron UpClose 20x50 Porro Binocular?
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4 votes

Depending on the season you can try different objects. Try large star clusters and nebulae: The Pleiades Orion nebula Andromeda galaxy M13 globular cluster Also double stars like epsilon Lyrae. It ...

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Are Barlow Lenses Good For Deep Sky Observing?
4 votes

It depends. The Barlow is usually a cheap shortcut for avoiding to buy an expensive short focal length eyepiece. Also you need Barlows and high magnification usually only for small objects. For ...

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How many planetary systems exist in our galaxy?
4 votes

According to observations by the Kepler space telescope and other ground based observations, it seems that about 5% of the stars in our galaxy have giant gas planets, similar to Jupiter (but often ...

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Coordinate transformations between reference frames in spherical astronomy
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3 votes

There is kind of an answer over at Math. All you can do in spherical coordinates is to change the position of your "pole", i.e. you have $(1,0,0)$ in your first coordinate system, which is mapped to ...

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Does the Reflection Method for Looking at the Sun Work For Refractors?
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3 votes

Actually, your Newtonian may run the risk of suffering from the projection method. The secondary, planar mirror in the Newtonian will be subject to heating. Although it is not in the prime focal point,...

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Where does the radiation in space come from and can we observe it?
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3 votes

Cosmic rays consist of both electromagnetic radiation (i.e. photons) of different frequencies (radio waves, IR, light, UV light, x-rays, gamma rays), as well as charged particles (protons, electrons, ...

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Collimator for Dobsonian, same as Newtonian?
2 votes

Yes, of course it will work. A Dobsonian is merely a Newtonian telescope on a special mount.

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Is there a natural process by which hydrogen is generated from heavier elements in the cosmos?
2 votes

It seems that primordial black holes produce anti protons, and it is implied in the linked article that they are capable of producing all kinds of other particles. So maybe even protons. Also, I guess ...

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