An Edgy Perspective

Stuck on Earth, we essentially get one viewpoint of the cosmos. From a seemingly fixed location in the universe, it doesn’t seem like other objects move very much, apart from the “wanderers,” as the Greeks called the planetes, or planets. The Earth’s axial tilt of 23.5 degrees, combined with orbiting the sun, gives us opportunities to view different parts of the night sky at different times of the year. This gives us the many constellations that, while they no longer match up to the ancient months of astrological charts, do progress through our skies over the course of one orbit, or year. Of course Earth is not the only body running laps around the sun, not the only planet that leans to the side, either.

‍

The early solar system was complete chaos. Over nearly 500 million years a giant cloud of gas and dust coalesced around the sun, and gravity pulled debris together into gassy and rocky clumps large and small. Run-ins between these bodies were common, and one such collision knocked the early Earth sideways, giving us our 23.5 degree tilt and seasons. While we can’t rewind and watch a replay of these planetary fouls, the telltale signs of these impacts are scattered across the system.

Ironically, Mars isn’t much different from Earth, with a tilt of 23.98 degrees. Jupiter can clearly take a punch, because it barely leans at 3 degrees. Saturn sits 26.73 degrees off kilter, and Uranus is completely sideways, rolling down its orbital plane at 98 degrees. Venus took a knockout blow at some point, as it spins on its axis at 177 degrees, or almost completely upside-down, and backward relative to everything else in our stellar neighborhood. The larger planets must have protected their little brother from these celestial scuffles, as Mercury is the only known body in our system with no tilt at all.

These cosmic accidents left debris fields in their wake, proof of which are the rings that grace the four gas giants of the outer solar system. Galileo was extremely perplexed by Saturn’s unique oblong shape as he gazed through his early telescope, and while he likely never fully understood it, those who followed have certainly been entranced by Saturn’s rings. Like countless astronomers before, seeing the rings of Saturn through a backyard telescope is what truly solidified this author’s passion for space.

Over 400 years of study have documented the changes in Saturn’s rings, from both far away and up close, and across the entire spectrum of visible and non-visible light. The Cassini probe orbited Saturn from 2004 to 2017 and gave us an understanding of the rings’ structure as billions of small pieces of snowy dust, ranging in size from a grain of sand to a small house. The overall depth of the rings averages less than 1 kilometer. Amazingly, at nearly 1 billion miles distant, we can still see these rings from our vantage point on Earth.

Sometimes.

Because Saturn is tilted at 26.73 degrees, we see the rings from different angles depending on how they align with our orbit. About every 14 years we see the rings completely edge-on, and they essentially disappear. During the month of March the rings will be at this angle relative to us, and seem invisible except to the largest of telescopes. Sadly, Saturn is extremely close to the sun this month and not visible to most amateur astronomers. However, as it emerges from behind the sun in the spring mornings later this year, the rings will again begin to tilt toward us, and offer backyard astronomers the world over one of the greatest sights in the heavens.