Cosmic Curiosities
“Our solar system is fantastically bizarre. There are worlds with features we never imagined. Storms larger than planets, moons with under-surface oceans, lakes of methane... And that's just at Saturn.”
- Phil Plait, American Astronomer
A Far-out Saturn Story
Solar System Tour Ship. Credit: Polyfjord
Imagine leaving Earth for a four-year trip to Saturn.
Your spaceship is luxurious. It reminds you of the ocean-faring cruiseships back on Earth. It will take almost two years to get to Saturn, and after a month of exploration, you and a thousand other passengers will head back home.
Credit: Microsoft Copilot
You finally arrive after a journey of almost a billion miles. Mars and Jupiter were impressive to behold as you passed those worlds for a gravity assist and save precious fuel. It was part of the reason planet-travel trips were finally affordable. Space tourism seems to keep growing!
Now, though, you gaze at impressive Saturn, the giant ring jewel, filling your spaceship window. You notice its layered clouds and recall its fast rotation, spinning once every 10.7 hours. The yellow color is striking. You ask the ship's computer the cause. It spits back quickly, “Saturn's marvelous yellow color is caused by the white ammonia haze that surrounds this globe—which is caused by its thick atmosphere, which is caused by its cold conditions—which is further caused because of its great distance from the sun. The cold ammonia clouds partially obscure the redder clouds below, giving Saturn a more yellow and captivating appearance.”
Credit: Microsoft Copilot
You recall a Planetarium field trip in grade school where they showed Saturn floating in a cosmic ocean. You smile at the memory: “Saturn's density is eight times less than Earth's at 0.7 g/cm3 (grams per cubic centimeter). Density equals mass divided by volume. Water's density is equal to 1.0 g/cm3. So, anything under one will float and anything over one will sink.”
The captain says it is time to travel through the rings. Long ago, NASA's spaceships discovered the rings are tiny chunks of water ice, rock, and dust. Some are as tiny as a grain of sand. Others are as large as a house. Water ice dominates. You laugh as you recall seeing Saturn's rings as a young kid. Your mom had a telescope in the backyard. Saturn and its rings always looked so tiny, like a flying saucer. When Galileo saw it more than 400 years ago, he remarked the rings looked like ears growing out of Saturn. Your reflections turn to mom. You place your hand over your heart, thanking her for the astronomy enticements.
After a week orbiting Saturn, your spaceship steers everyone toward Saturn's huge moon, Titan. It is the second-largest moon in the solar system; only Jupiter's Ganymede is larger. It has long been known that Titan has a thick nitrogen atmosphere, so no telescope could see its surface to explore what lurks below. That changed in 2005 with the Huygens probe, part of the Cassini mission, a joint effort by NASA and the European Space Agency (ESA).
Left: Real picture of Titan's surface and an artist interpretation. Right Credit: European Space Agency
The major surprise at Titan was the discovery of liquid methane and ethane lakes on its surface. This subsurface ocean was a genuinely exciting find, raising humanity's most profound question: Could life exist here, beyond planet Earth? The Huygens probe could not answer that alien mystery. No one has since. You sit back in your chair as your mind muses effortlessly on the possibilities of extraterrestrial life.
This distant planet trek has three more weeks here at the Saturn system. Many fly-bys of Saturn's other moons lay ahead. You are most excited about witnessing Enceladus and its icy geysers up close. Only a few more days... That will be awesome!
You fall asleep in your space cabin, dreaming of a futuristic voyage to the stars.
Pluto Power!
Our views on Pluto have changed quite a bit throughout the years. Soon, we will celebrate the 100th anniversary of its discovery by Clyde Tombaugh in 1930!
Our views of Pluto from 1930 to today. Credit: NASA
This small world still fascinates people. Many long for it to be a planet again, upset that in 2006, Pluto became a dwarf planet. They love the nostalgia of it once being the smallest planet, the underdog, the forgotten, distant, and mysterious planet. Pluto's location is in the far-off Kuiper belt, where the sun's rays barely heat its icy surface. With its extreme distance and dark appearance, it is fitting that Pluto was named for the Roman god of the underworld.
The discovery of Pluto involves studies on the ice giants. Uranus' orbit was irregular. Another object was tugging on it. The gravity calculations said “look here” and, lo and behold, we discovered Neptune in 1846! But some scientists asserted that there must be another object farther out, a hypothetical “Planet X,” tugging on Neptune. The effort to find this new planet was led by Percival Lowell, who hired Clyde Tombaugh to go planet hunting. After 7,000 hours of comparing the same images taken on different nights, Tombaugh saw a “star” move. This tiny, far-off speck of light was the planet Pluto.
Tombaugh's Pluto on photographic glass plate, found via blink comparator. Credit: Lowell Observatory
Advancements in telescopes and the launch of Hubble in 1990 allowed scientists a more detailed glimpse of our far-off neighbor, but Pluto was still fuzzy.
Thus, in 2006, New Horizons rocketed off to make an official visit, revealing a cratered, frozen dwarf planet with a heart-shaped plane of ice in 2015. The moon Charon was also photographed, revealing a surface much different than Pluto. Astronomers are still analyzing all the images and data from the New Horizons spacecraft.
Pluto & Charon; Credit: NASA
Pluto is not a dead-far, frozen rock. It is a geologically rich world. Pluto may have a subterranean ocean, so cryovolcanic activity is not out of the realm of possibility. With cryovolcanoes, ice and water function as the equivalent of rock and magma on terrestrial planets, and eruptions are driven by internal heat. On Pluto, scientists have already identified and labeled two mountains, Wright Mons and Piccard Mons, as possible cryovolcanoes. Recently, scientists have reassessed an impact crater, Kiladze, as a potential super-cryovolcanic caldera, comparing its form to Yellowstone's caldera in Wyoming. It has an average diameter of 2.5 miles, and its ovular shape is like other impact craters. Its depth is far too great at an average of two miles, with some parts as deep as the crater is wide. This cataclysmic event which may have led to the caldera's collapse would have spread cryo-magma at least 600 miles!
Kiladze Impact Crater. Credit: USGS Astrogeology Science Center
However, scientists did identify a unique ammonia compound in the ice around the Kiladze crater. Pure ammonia does not last long in cold space, so its mere presence suggests that Kiladze might have erupted recently. Additionally, Pluto's atmosphere contains an icy nitrogen haze, with the particles slowly falling back to coat the planet. But this falling haze has not buried the area around Kiladze, pointing to a recent eruption—possibly. This means Pluto's interior may still retain warmth and be active with cryovolcanoes!
All told, it is heartwarming to learn that despite its icy exterior, people still care about Pluto and its secrets. Fittingly, its iconic heart-shaped region and brightest part of Pluto’s surface is named Tombaugh Regio, after the man who brought the dwarf planet out of the underworld and into the light.
Upcoming Eclipses
Left: Lunar Eclipse September 7; Right: Solar Eclipse September 21. Credit: timeanddate
Both lunar and solar eclipses occur this month, but neither is visible in Wisconsin. See the maps above for exact locations.
In 2026, we will see three eclipses—if clear skies prevail. There will be a lunar eclipse on March 3 and August 27, plus a tiny partial solar eclipse on August 12.
Space in Sixty Seconds
Detect Saturn in the night sky, then dive into its rings and icy moon, Enceladus.
Sky Sights
Venus and Jupiter still dominate the morning sky. Watch them all month near the two bright stars in Gemini, Castor and Pollux.
Saturn and the Moon join forces on September 7 and 8. The ring planet is at opposition on September 21. This means Saturn is opposite the sun. It rises at sunset and sets at sunrise. When the Moon is full on September 7, it is at opposition.
The waning crescent Moon joins the two bright planets from August 19 to 21. Notice how far apart Venus and Jupiter are just five days later.
Mars and the bright star Spica in Virgo will be a tough sight to see this month and the rest of the year. The red planet is at solar conjunction—behind the sun—on January 9, 2026. It will reappear in the morning sky, but not until March 2026.
The waning crescent Moon lines up with Venus and the bright star Regulus in Leo the Lion on September 19. Bring a pair of binoculars for this close cosmic gathering. And remember, these three are not close; our best spaceship can get to the moon in a few days, to Venus in just months, but to continue to Regulus would take another 2 million years!
Catch a growing crescent Moon move low across the southern sky in the constellations Scorpius from September 26 to 28.
Mercury is too close to the sun to spot in the night sky this month.
September Star Map
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