Editing 3156: Planetary Rings

{{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}} and {{w|ice giant}} planets in the Solar System have rings, as may (possibly transiently, due to interactions with other bodies) some of the {{w|minor planet}}s and even {{w|asteroid}}s.

Earth does not have a natural ring system, nor currently any of the other {{w|terrestrial planet}}s, although it's theorized that it [https://web.archive.org/web/20250401024532/https://time.com/7022440/earth-ring-like-saturn-study/ may have had one] in the distant past. However, since the 1950s (slightly over 68 years before this comic's publication), we have launched many [https://satellitetracker3d.com/track?norad-id=26548/ artificial satellites into Earth orbit]. The ones specifically in {{w|geostationary orbit}} (the {{w|Syncom|first}} of these being launched in 1964) are in the equatorial plane (as are some with different {{w|orbital period}}s), so they can be considered to constitute an artificial ring system. (Other satellites operate within various other {{w|orbital plane}}s, including {{w|geosynchronous orbit}}s that are not strictly geostationary, creating {{w|File:Starlink_SpaceX_1584_satellites_72_Planes_22each.png|various other}} halo-like clouds.)

{{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}} in middle and low latitudes, or a {{w|Molniya orbit}} satellite constellation in higher latitudes. 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. 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, so if a dish moves, that doesn't prove that it ''isn't'' using geostationary satellites. Also, there are antennas which can "point" at different directions by {{w|Phased array|electronic means}}, without physically moving (e.g. {{w|Starlink}} user terminals, which have to make contact with one or more satellites passing rapidly overhead in a far lower orbit) that may therefore just be pointing 'generally up' without physcally being dynamically angled towards any particular satellite position.

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 ([https://www.science.org/doi/10.1126/science.aat2965 10<sup>19</sup>&nbsp;kg]), Uranus ({{w|Rings of Uranus|10<sup>16</sup>&nbsp;kg}}), Jupiter ([https://pages.astro.umd.edu/~dphamil/research/preprints/BurSimSho03.pdf between 10<sup>11</sup> and 10<sup>16</sup>&nbsp;kg]) and Neptune ({{w|Rings of Neptune|10<sup>15</sup>&nbsp;kg}}). Assuming 580 satellites (active and inactive, 1/2° slots) {{w|List of satellites in geosynchronous orbit|in geostationary orbit}}, and a typical mass of 1,000&nbsp;kg, Earth's ring system has a mass of 5.8x10<sup>5</sup>&nbsp;kg (580,000&nbsp;kg).

==Transcript==

:[On the left side of the single panel, a table with words in one column and checkboxes in the second:]
:[Two Column headers, underlined:]
:Planet
:Rings? 
:[Table entries, by line:]
:Mercury [Unticked checkbox]
:Venus [Unticked checkbox]
:Earth [Originally unticked checkbox, now with a red tick added]
:Mars [Unticked checkbox]
:Jupiter [Ticked checkbox]
:Saturn [Ticked checkbox]
:Uranus [Ticked checkbox]
:Neptune [Ticked checkbox]

:[On the right side of the single panel, an illustration of the Earth from space, with Africa most obvious and centrally in view. Many dots represent satellites, a lot of them close into the Earth but an even more significant number of them are in a very wide and tilted ellipse depicting a large circular orbit seen from a highly oblique angle. A labeled arrow points to the ellipse:]
: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:Facts]]
[[Category:Astronomy]]
[[Category:Comics with color]]
[[Category:Comics with red annotations]] <!-- the single tick that it is... -->