Hot answers tagged

45

You don't say what time you were looking. Here is a screenshot from Stellarium at 10pm Wisconsin time on 25th March 2016. Jupiter is in the ESE, but the altitude is a bit lower than 60 degrees. Seems fairly conclusive. You were seeing Ganymede and a Europa/Io combination.


35

That should be Jupiter and his 4 Galilean moons. They are usually very well visible even with very cheap equipment and a nice experience for amateur astronomy. On your picture 2 of them seem missing, maybe they were cut-off by the field-of-view, or possibly as a commenter pointed out, they might be behind the planet. You can test that notion actually, as ...


31

This has been done before, so I don't have to go through all the heavy calculations using Rayleigh criterion accounting for atmospheric diffraction and visible light wavelength. Ralf Vandebergh, a Dutch astronomer, professional photographer and veteran satellite spotter has been busy trying to do exactly this since the 2007 and has indeed succeeded on ...


19

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 an off the shelf telescope. He supposedly has imaged spacewalkers on previous ISS and STS missions. Though they are only a few pixels in size, and you cannot ...


16

This appears to be Jupiter and two of its four "Galilean" moons, being the four discovered by Galileo with his telescope in 1610. I searched with Wolfram Alpha (http://www.wolframalpha.com/input/?i=jupiter+moon+configuration+march+25th+2016+9pm+US+central+time) to try and determine which moons you were looking at, and the answer was quite interesting. ...


15

A lot of satellites are visible under the right conditions. Usually up to 2 hours after sunset and 2 hours before sunrise. This allows the sun to strike the satellite when you are on the dark side. Depending on the orbit, it will take between 1 and 5 minutes to traverse most of the sky. Usually, they will enter the shadow and you lose sight of them.


13

The term "color" is a label that humans have assigned to denote the ratio between the intensity at various wavelengths in the three different wavelength bands, or regions, that the human eye is able to perceive. These bands are centered roughly at 430, 545, and 570 nm, but are quite broad and even overlap: Human cone response, normalized to the same ...


12

This is actually quite straightforward with digital CCD's (it used to be quite tricky with film cameras as you'd have to carefully develop film that moved past the lens and assess the width of the trail) Get yourself a good telescope - a 12" Dobsonian or above if you want to give yourself a good chance of picking out the fluctuations against the noise ...


12

telescope.com has a quick paragraph on astronomy. Below I summarise the important points with a few of my own suggestions thrown in. Dark & dirty places Set up on grass or dirt, pavements and buildings radiate the heat again at night and the air flow created by this can distort your image. If possible you might be able to make use of a public park. ...


11

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), and they use an eyepiece with another lense system (for viewing) or a camera in their primary focus. A refractor telescope does not sharpen the image per se. ...


11

You possibly are confused by these two entries in Wikipedia (click on the quotations to go to the original distinct entries: Canis Minor contains only two stars brighter than the fourth magnitude, Procyon (Alpha Canis Minoris), with a magnitude of 0.34, and Gomeisa (Beta Canis Minoris), with a magnitude of 2.9. and This is the list of [56] notable stars ...


10

@Arne is right in his answer about two things, that the most suitable frequency for Jovian amateur radio is 20.1 MHz, and that this is a 15 meter wavelength. However, the antenna can actually be half the wavelength, and amateur radio astronomers have had good results listening to all kinds of Jovian sounds, including detecting occultations of its many moons ...


10

Globular clusters occupy an interesting place in the spectrum of composite stellar systems. As you point out, they are highly concentrated populations of stars, and seem to lack any dark matter component, unlike more massive dwarf galaxies. Binary interactions become very important in simulating globular clusters, and interestingly enough (maybe ...


8

Well, because the axis of the rotation of the Earth is not the same as the axis of rotation of the disk of the Milky Way (and also because we're transforming a 2-dimensional spherical map into a 2-dimensional cartesian map), the path of the disk of the Milky Way galaxy looks something like this: So, there is actually a wide range in declination that the ...


8

Any telescope can be made to give you the information that you are looking for. The first thing that you will need to know is the location of the ecliptic which varies throughout the year. Or are you looking to find in relation to the the celestial equator? https://en.wikipedia.org/wiki/Celestial_equator Either way, you would start of the same by find ...


8

As you say, SN 1572 is not very bright in the optical. There are some Hα regions that have been observed with world-class optical telescopes, but they do not look like the X-ray and infrared images that you normally see. In fact, images from the Palomar Optical Sky Survey 2 (with a limiting magnitude of ~22) do not reveal any nebular emission from ...


8

Your guess was correct. It is the Andromeda Galaxy, M31. Here is a map of the part of the sky near zenith at the place and time you provided: Sky map for Taganrog, Russia on 11/23/2013 5:00:00 PM UTC. Even the rotation is small. The sky map is rotated approximately 30° counter clockwise relative to the photo. You were approximately facing south when taking ...


8

In your friends picture are more artifacts than the one you showed in the 2nd picture a little bigger. I marked more of them in the picture below. They are all in a perfect line to the bright light. So these artifacts are caused by the bright light and the lens of the camera. A lens is not flat it's, well lenticular (it's where the name came from). The ...


8

The video is hilariously wrong. However, the principle of laser ranging is more or less right, and it does require the reflectors left behind by the astronauts on the Moon. It's just that the physics and technology involved are far beyond just pointing a toy laser at the Moon. Project APOLLO (Apache Point Observatory Lunar Laser-ranging Operation) is ...


7

As for projecting the Sun onto a screen at a low cost, I would recommend starting with a ~50-200$ sunspotter box, which is basically a lens mounted on a wooden box, that projects the sun onto a white piece of card. The advantage of using a telescope is that it can be programmed to track the Sun, so that if you want to trace sunspots, for instance, you can do ...


7

You're experiencing a few issues all of which have one solution. Take the Scope outside. Let it acclimate to the ambient air tempurature, and then try looking. The 1st issue is the mirror needs to be the same temp as the air you're observing in. Since you are indoors you have a very warm optical path this causes distortion and trouble focusing. 2: Because ...


7

There aren't any. A 25-30 $M_{\odot}$ main sequence star would have a spectral type of $\sim$ O7 and an absolute $V$ magnitude $M_V \simeq -5$ (see Zombeck 1982). A giant star with this mass would be even more luminous. At a distance of 30pc, the apparent magnitude of such a star would be $V=-2.6$. Closer examples would of course be brighter. Sirius is the ...


7

Aabaakawad's answer highlights an important aspect of any constellation: They are defined by a surface area on the sky, behind which many, many stars hide. In order to answer just how many stars, you'll have to ask "above which brightness threshold?". I think you should accept his answer, but I have two comments: "…if one were to map every star visible to ...


6

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 tracker on top. There is a variety of products like: iOptron Sky Tracker Vixen Polarie They cost around 400-500 USD and are fairly small. You need to align ...


6

Yes, there are filters which do block out the vast majority of light from the sun. I think it's actually only a very small (~1 angstrom) wavelength band of light which gets through. You can see some pretty amazing features, including sunspots, and solar flares. Here's a composite image as an example (taken through a Hydrogen alpha filter): Those smallish ...


6

Is there any publicly available, NEO-related database out there? Or is there a specific institution a hobby-astronomer can/should turn to to be able to learn more about individual NEOs? Yes, there is NASA's Near Earth Object Program that catalogues all detected NEO's and had advanced reporting and seearch capabilities (a bit overwhelming number of ...


6

The answer is right there in your screenshots. The 'dimensione' or angular diameter on the sky is 3 degrees for M31, whereas the moon has an angular diameter of only 0.5 degrees. In other words, M31 is about 6 times as wide as the moon. As wikipedia correctly states, you need a large telescope to see the full extend of M31. With the naked eye of even a ...


6

In a typical position in a globular cluster (maybe halfway between center and edge), there'd be many more bright stars in the sky due to the star density. These would be distributed unevenly in the sky, with more light coming from the center of the globular cluster. Depending on the globular cluster's orbit, we might be able to see the Milky Way face-on. ...


6

Given the description, that light patch was probably Pleiades. It is a star cluster in the constellation of Taurus which is inspired from a popular Greek mythology of Seven Sisters. You can read more about it here. EDIT: One of the great softwares, free and open source, for amateur level observational astronomy, though professionals use it as frequently ...



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