3219: Planets and Bright Stars
| Planets and Bright Stars |
 Title text: An old astronomer trick for distinguishing the Sun from other stars is to take multiple photos a few minutes apart and overlay them, making the Sun stand out due to its high proper motion. |
Explanation
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This is one of 75 incomplete explanations: This page was created by a GLOWING SPACE DOT. Don't remove this notice too soon. If you can fix this issue, edit the page! |
This comic features a chart of a handful of cosmic objects and what they look like in the night sky. The joke is that they are all nearly identical dots, making the chart almost useless.
The comic shows an identification chart for some of the planet and bright stars visible at night from Earth. Bright shiny objects are often confused by people without astronomical experience, and the chart is supposed to make this easier by placing them adjacent to one another to easily see the differences. The joke is that the pictures look almost identical to one another, and therefore the chart isn't helpful at all.
The real way of distinguishing these objects is by their location on the sky. The stars will be possible to find by the use of constellations, which are apparent pattern of bright stars that make different regions of the sky distinguishable from one another. The planets can be distinguished by not belonging to the constellations, and further differentiated by their color, brightness, and movement relative to the stars (on the scale of weeks or months).
Selected objects do indeed look similar to one another in reality, but not identical. Some of them (in particular, the star Betelgeuse and the planet Mars) have a distinct reddish color, which can be seen in good conditions. The brightness is also different, and it can serve as a guide, but it's difficult to precisely judge brightness by eye, and the planets don't have a constant brightness over time. The differences are actually visible in the comic to a degree - e.g., the spots for Venus and Jupiter are slightly larger than the others - but they're subtle enough to not recognize at the first glance.
Each 'object' also has a colour, albeit extremely desaturated (very nearly white). If deliberately exagerated, the planets and suns are all notably non-white. Of the planets, Venus can be seen to have the yellowy-orange hue of its cloud layers, Mars is red (reflecting its surface; and substantially less so, in its raw image, than an observer might experience with its real-life counterpart in the night sky, but probably muted for the sake of the joke), Jupiter has the more orange hue of its combined cloud layers, Saturn is a more 'peachy' orange (of its clouds, and no obvious hint of its rings), Mercury has a Sun-bleached yellow (normally only seen in enhanced-colour images). For the stars, Sirius (being a main-sequence A-type star) is a light blue, Procyon (F-type star) might be identified as closer to a light green, Anteres (M-type star) is orange, Altair (A-type) another light blue, Betelgeuse (M-type) a relatively dark red, Vega (A-type) another light blue and Polaris (actually a triple-system of stars, dominated by an F-type supergiant) the most subtle blue of all.
Using even a small telescope would make it easy to distinguish the planets by their brightness, size, and surface features. Additionally, using a spectroscope would allow for a measurement of the star's spectrum, which coupled with its brightness would allow an astronomer to easily distinguish between mentioned stars.
The title text suggests a "trick" for recognizing the Sun among other stars, suggesting measuring its proper motion (a measure of the angular component of a star's motion, in radians per second, perpendicular to the radial velocity vector) by overlaying several images. This does indeed differentiate it from other stars, but there are much easier methods, such as its extreme brightness and large angular size.[citation needed] It is also completely unnecessary, except during a solar eclipse, because stars are not usually visible during the day, when the Sun is out. Additionally, "proper motion" is a term usually not used for the Sun.
Transcript
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This is one of 46 incomplete transcripts: Don't remove this notice too soon. If you can fix this issue, edit the page! |
- [Caption: Planets and bright stars identification chart:]
- [A 4x3 grid of planets and stars are displayed on a black background. White text below dots of light caption which object it is. Planets and stars are represented by almost-identical slightly fuzzy dots of white light.]
- Venus
- Mars
- Jupiter
- Saturn
- Mercury
- Sirius
- Procyon
- Antares
- Altair
- Betelgeuse
- Vega
- Polaris
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