# Tag Info

36

Constellations are human constructs to make sense of the night sky. When you are trying to find your way around, it helps to "chunk" stars into patterns and assign those groupings names. When I want to point out a particular object in the sky (say Polaris, the North Star), I start by pointing out a familiar constellation (say Ursa Major, the Big Dipper). ...

23

The stars are so immensely far away that to the human eye there would be no noticeable difference. The nearest stars are moving roughly 1.5 arcsecond wrt. the background when viewed from Earth's position with half a year's interval (i.e. half a revolution around the Sun). Mars' orbit is only 50% larger, but the human eye cannot resolve better than roughly ...

22

If you set the date to 2018-04-06, Stellarium shows the Moon and planets in positions matching the example image. Any good planetarium software should produce a similar result. Most likely the vendor cut and pasted two screenshots (note the seam) for April 2018, overlaid "January 1973," and hoped customers would not check. Perhaps you could ask them to send ...

18

What you describe is a technique called averted vision and takes advantage of the arrangement of cones and rods, two types of light sensitive elements within the eye: The retina contains two types of photoreceptors, rods and cones. The rods are more numerous, some 120 million, and are more sensitive than the cones. However, they are not sensitive to ...

18

The terms refer to the viewing angle, i.e. from which direction do we observe a (disk) galaxy. If we happen to be located roughly in its plane of rotation, we see it from the "edge", whereas if we are more or less above or below its plane, we see its "face". To make a more quantitative statement, the orientation is described by the inclination angle $i$, ...

17

It is true that, for an observer standing on Earth, the daytime sky blocks out our ability to see the stars (with the exception that stars are visible during a total eclipse). It is possible to get pretty close. In a different post, it was asked if the the center of the galaxy is only visible for 1/2 of the days of the year. That post is here: Is it true ...

16

No, it does not. The constellations are fixed (on time scales long enough for humans to consider as fixed, at least) patterns of stars which exist on the celestial sphere. This celestial sphere is a coordinate system which has the Earth at its center. From the Earth's perspective, the sun rises and sets at the same rate as the constellations, but as the ...

16

I just want to add pictures to augment pela's answer. Just google "edge on galaxy" and "face on galaxy" to find results like these, it is entirely about the viewing angle. Example of a face on galaxy (Messier 74) Example of an edge on galaxy (NGC 891)

13

If the stars are all similar distance from us, like the Pleiades, then yes, you could find a place from where the stars would appear in a similar pattern and brightness, but the pattern would be a mirror image. You can't do it when the stars are significantly different distances because they wouldn't look the same. Most constellations are a range of ...

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 ...

11

The short answer is there are no galaxies in or around Orion that are visible to the naked eye. The International Astronomical Union (IAU) has some simplified star charts for each constellation. The charts show galaxies the brightest galaxies that are visible in amateur telescopes as red ovals. The chart for Orion and the surrounding constellations show no ...

10

Constellations and asterisms are generally not proximate in space, but rather happen to be nearby only when viewed from Earth. From Wikipedia's article on asterisms: Like constellations, asterisms are in most cases composed of stars which, while they are visible in the same general direction, are not physically related, often being at significantly ...

10

The device that you saw is called a nocturnal. It calculates the local time based on the month of the year and the position of Polaris and one or more other stars. Since stars change position throughout the night, they can be used to determine time; but the positions of stars change throughout the year, so the input of the month of the year is needed. ...

8

These are the Latin word endings. Latin nouns change their endings according to how the word is being used. English doesn't have this grammar. But note how the word "I" changes to "my". In Latin you would call "my" the genitive form of "I" The good people at https://latin.stackexchange.com/ can give more explanation. For example, "Leo" is a third ...

8

There are no naked eye galaxies in Orion. The brightest galaxies in Orion are NGC1924 (a magnitude 13 barred spiral, 130 million lightyear distant) and IC421 (a magnitude 14 spiral that hosted a supernova visible in 2013, 150 million ly distant) In the neighbouring constellation of Eriandus is NGC1600 (a large elliptical galaxy with magnitude 12 with an ...

7

Nope, that constellation is Perseus.

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 ...

7

To calculate that you will have to build a 3D model based upon the distance of each of their stars and then calculate the resulting 3D object's volume. I know this may not answer the question, but I give the way to answering it. It's not an easy job. Making a quick guess based upon the distances of the stars of both constellations in my opinion I guess the ...

7

Quoting from wikipedia: Canis Minor was one of the original 48 constellations formulated by Ptolemy in his second-century Almagest, in which it was defined as a specific pattern (asterism) of stars; Ptolemy identified only two stars and hence no depiction was possible. The Ancient Greeks called the constellation προκυων/Procyon, "coming before the dog", ...

7

The constellations are artifacts of visual pattern recognition, many dating back to antiquity. As the stars are distributed unevenly, naturally some constellations are larger than others. Ptolemy catalogued 48 of them around 150 CE. The other 40 were added between 1596 and 1763, either to cover the far southern sky or to fill gaps between the older figures. ...

6

There are thirteen modern constellations in the Zodiac. In modern astronomy, a constellation is a specific area of the celestial sphere as defined by the International Astronomical Union. In total, there are 88 constellations. Astronomy and Astrology are not the same thing. Astronomy is a science while Astrology is not. As such, I'll restrict myself to the ...

6

This obviously depends on which stars you choose, but in general Ursa Major is likely to win by a factor of about five(ish), since it occupies a much larger chunk of the sky (1280 square degrees) than Ursa Minor (256 square degrees). At a fixed magnitude, and therefore at a fixed visibility radius for each intrinsic luminosity, the volume will be (very ...

6

Yes, there are exo-planets discovered in the Orion constellation, for instance, the stars HD 37605 and HD 38529 both have two known planets. HD 38858 is also interesting, as it has a known planet, and also a disk of comets.

6

The March equinox would be a good time to see both; the September equinox would not. Crux lies roughly between RA 12h to 13h, Dec -55$^\circ$ to -65$^\circ$. For best results, be at latitude 10-15$^\circ$ N so that both Crux and Polaris are well above the horizon, and look between 11:00 and 14:00 local sidereal time so that Crux is near the meridian. That ...

6

As others have said, Orion (and other constellations) only looks the way it does from a specific angle. The stars are distributed at different distances from Earth, so from a different position, including directly "behind" it, it would look quite different. Here is a (terrestrial) example of something that looks different depending on the angle that it's ...

5

The common explanation is linked to the eye structure: in the center of the eye, you have mostly cones, that are used to detect colors and that are efficient only in bright light (that's why we don't see colors so well during the night). The rest of the eye contains more rods, that are used to detect dim light and contrast. So the best way to observe some ...

5

The stars in any given constellation can be at vastly different distances, there is no link between the distance and the size of a constellation. The constellation boundaries are purely artificial boundaries.

5

Stars with an apparent magnitude of 7.0 or greater are typically not visible to the naked eye. So if you take a list of exoplanetary host stars, such as this, and you sort by apparent magnitude, in ascending order, then you will see a list of identifiable stars known to have exoplanets, until you reach an apparent magnitude of 7.0 on the list. Finding the ...

5

This is from an article in the Conversation, by Duane W. Hamacher, and Carla Bento Guedes: "Voyagers measure the angles between stars and the horizon using their hands. The width of your pinkie finger at arm’s length is roughly one degree, or double the angular diameter of the Sun or Moon. Hold your hand with the palm facing outward and thumb fully ...

5

In traditional constellation shapes / outlines, yes. But the International Astronomical Union (IAU) standardised on a set of 88 constellations in 1922, and from 1924 to 1930 formalised the constellation boundaries, splitting the sky into separarate areas (that cover the complete sky) so there's no ambiguity now. For example, before the constellations were ...

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