3156: Planetary Rings

2025-10-17T19:25:24Z

2001:4C4E:1C01:CC00:E9F3:4076:7512:7BFC: /* Explanation */

{{comic
| number = 3156
| date = October 17, 2025
| title = Planetary Rings
| image = planetary_rings_2x.png
| imagesize = 356x279px
| noexpand = true
| titletext = If you don't know where you are on Earth, the angle of satellite dishes can help constrain your latitude. If some of them are pointing straight up, you're probably near the Equator, right under the ring.
}}

==Explanation==
{{incomplete|This page was created by an off-axis satellite dish. Don't remove this notice too soon.}}
A {{w|ring system|planetary ring}} is a disc of small objects and other material orbiting a planet. The most well known are the rings of {{w|Saturn}}, which were discovered by {{w|Galileo Galilei}}, but all the {{w|gas giant}} planets in the Solar System have rings, as do some minor planets and moons.

Earth does not have a natural ring system, although it's theorized that it may have had one in the distant past.[https://web.archive.org/web/20250401024532/https://time.com/7022440/earth-ring-like-saturn-study/] However, since the 1950's (about 68 years ago at the time this comic was posted) we have launched many artificial satellites into Earth orbit, and the ones in the {{w|Geostationary Orbit}} are in the equatorial plane, so they constitute an artificial ring system. (Other satellites are in various {{w|orbital planes}}.)

{{w|Satellite dishes}} are used to communicate with most of these devices. If they are stationary that means they are pointed at a {{w|geostationary satellite}}. Not all dishes are pointed at the geostationary orbit, but in that case, if they are used for communicating with satellites in other orbits or with space probes, they must move continuously to track the satellite/probe.

(Note 1 - there are motorized dishes that can move between some number of pre-programmed positions to select which geostationary satellite to use at a given moment.
Note 2 - there are antennas which can "point" at different directions by {{w|Phased array|electronic means}}, without physically moving (eg, {{w|Starlink}} user terminals).)

In terms of mass, Earth's ring system is tiny compared to other planetary ring systems in the Solar System. In descending order of mass, these are Saturn (1019 kg [https://www.science.org/doi/10.1126/science.aat2965]), Uranus (1016 kg [https://en.wikipedia.org/wiki/Rings_of_Uranus]), Jupiter (between 1011 and 1016 kg [https://pages.astro.umd.edu/~dphamil/research/preprints/BurSimSho03.pdf]), Neptune (1015 kg [https://en.wikipedia.org/wiki/Rings_of_Neptune]). Assuming 580 satellites (active and inactive) in geostationary orbit [https://en.wikipedia.org/wiki/List_of_satellites_in_geosynchronous_orbit] and a typical mass of 1,000 kg, Earth's ring system has a mass of 580,000 kg.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

:[On the left side, a table:]
: Planet Ring?
: Mercury ☐
: Venus ☐
: Earth [[☑]]
: Mars ☐
: Jupiter ☑
: Saturn ☑
: Uranus ☑
: Neptune ☑

:[On the right side, a drawing of the Earth from space, with Africa in view. Many dots represent the satellites, and most of them are in an ellipse. An arrow points to it:]
:Geostationary satellite belt

:[Caption below the panel:]
: Astronomy fact: a century ago, Earth didn't have rings, but we have one now! It's where all the satellite dishes are pointed.

{{comic discussion}}<noinclude>

[[Category:Astronomy]]
[[Category:Comics with color]]

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3156: Planetary Rings