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Pierce College Science Dome, 9401 Farwest Drive SW, Lakewood, WA (2026)

10/07/2026

It’s time to kick off the “busy” season for fall and early winter meteor showers! The Draconid meteor shower may not be the most prolific, but there’s a chance we could see a meteor storm this year. So read on to refresh your memory about what a meteor shower is and how you can check out this somewhat odd event!

⭐ What is a meteor shower?
A meteor shower occurs when Earth passes through a debris field left behind by an orbiting comet or, sometimes, an asteroid. When a comet gets close to the Sun in its elliptical orbit, it warms up enough to v***rize some of the ice, which carries dust and other small particles away from the comet and into space. As Earth orbits the Sun, it passes through the debris trail left by the melting comet and some of those small particles enter our atmosphere and burn up, producing bright streaks in the sky.

Meteor showers are usually named for the constellation from which the meteors appear to originate. The meteors aren’t actually originating from the constellation – it’s just a reference point for the direction from which the debris field is hitting Earth as we move along in our orbit. We call the apparent origination point the radiant. The radiant for the Draconids is in the constellation Draco (the dragon), near the stars Eltanin and Rastaban in the dragon’s head.

⭐ What is the Draconid meteor shower?
The Draconid meteor shower (Draconids; also sometimes called the Giacobinids) is an atypical meteor shower in that the best chance to see the most meteors is right after darkness falls, and not the typical best viewing time of the early morning hours after midnight. That’s because the constellation Draco is highest in the sky in the hours after sunset, and it stays pretty low in the sky throughout the night. Most years, the Draconids produce only a handful of relatively slow-moving meteors per hour.

The source of Draconid meteors (called a parent comet) is Comet 21P/Giacobini-Zinner, which was first discovered in 1900 by French astronomer Michel Giacobini and later confirmed by Ernst Zinner in 1913. Giacobini-Zinner is about 1.24 miles in diameter and orbits the Sun about every 6.6 years. The last time it reached its closest approach to the Sun (called perihelion) was in 2025 and the next will be in 2031. Giacobini-Zinner tends to bunch up its debris close to itself instead of spreading it out uniformly around its orbit, so when it is at perihelion there could be a lot of concentrated debris left in Earth’s orbital path. Since Giacobini-Zinner was at perihelion last year, there’s a chance that this year’s shower could be a storm.

⭐ What is a meteor storm and will we see one this year?
A meteor storm is a rare event where a meteor shower produces an exceptionally high number of meteors, often between 1,000 to 100,000 per hour! Meteor storms occur when Earth crosses a particularly dense debris field left by a comet that recently reached perihelion. The Draconids have been known to produce hundreds or even thousands of meteors per hour during a storm. In the years 1933 and 1946, observers saw several thousand per hour, but that’s not the case with every storm. In 1985, 1998, and 2018, there were more meteors than usual, but not quite enough to be considered a “storm”. But, since comet Giacobini-Zinner reached perihelion in March of last year, there’s a chance we could see more meteors than usual, but there’s no guarantee that we will see a storm.

⭐ How can I see the Draconids?
The entire Draconids event occurs between October 6th and 10th, but the peak is predicted to be on October 8th. Your best chance to see meteors will be the evening of October 8th, after the sky is dark. The Moon will be a waning crescent, so it shouldn’t interfere with the view much, but our typical October clouds might! If you are lucky enough to peek the clear sky, look towards constellation Draco in the northwestern sky, not far from the Little Dipper. Though the meteors will appear to originate from Draco, you can see them in a much wider area of the sky. So, you’ll want to look in the general direction of Draco, but not necessarily directly at the constellation. Remember to pick a spot that is far away from artificial lights and allow your eyes time to adjust to the dark. At its peak, the Draconids produce around 10 meteors per hour and you will be able to see them with your naked eyes.

Good luck and happy viewing!

📷: The radiant for the Draconid meteor shower is within constellation Draco. Via EarthSky.org

10/06/2026

Playing This Week at the Science Dome!

🌙 Moons: Worlds of Mystery - Wednesday, October 7th, 5:15pm
Experience the amazing diversity of moons and the important roles they play in shaping our solar system.

👑 Cosmic Legacy: Tribute to Queen - Wednesday, October 7th, 6:30pm
On-screen visuals guide you on a hypnotic journey that inspires nostalgia with hits like ‘Bohemian Rhapsody’, ‘We Will Rock You’ and ‘Love of My Life’. Celebrate Queen’s cosmic legacy with music and visuals that will take you to galaxies of emotions!

🌎 Habitat Earth - Friday, October 9th, 6pm
Journey to new heights to witness the intricate intersection between human and ecological networks.

🎶 Pink Floyd - Friday, October 9th, 7:15pm
A truly immersive and all-encompassing surround sound and visual treat that will transcend reality and take you way beyond the realms of 2D experience.

🎙️ Global Soundscapes - Saturday, October 10th, 3:30pm
With Global Soundscapes’ unique format—combining giant screen images, surround sound, and live presentation—you’ll hear the Earth in a whole new way!

👩‍🚀 Mars: The Ultimate Voyage - Saturday, October 10th, 4:45pm
Ever wondered what it will take for astronauts to travel to the Moon, Mars and beyond?

👑 Cosmic Legacy: Tribute to Queen - Saturday, October 10th, 6pm

Each all-ages public show features a 30-minute live night sky talk in the planetarium PLUS a 30-minute fulldome video (except for music shows, which do not include a live talk).

$8 general admission (except for music shows, which are $15)
Pierce College Students are free with ID

09/30/2026

On October 4th, Saturn will reach opposition for the first and last time in 2026, marking the best time of year to view our favorite ringed planet. Read on to learn more about planetary opposition, what Saturn will look like at opposition, and how best to view the bright planet!

⭐ What is planetary opposition?
Opposition occurs when a superior (outer) planet is on the opposite side of the sky from the Sun, as observed from Earth. When Saturn is at opposition, Earth will be directly between the Sun and Saturn. Opposition is the best time of year to view a planet because it will appear brighter and closer to Earth, and it is usually visible for the entire night. During its opposition this year, Saturn will be about 784 million miles (about 70 light-minutes) away from Earth, which is a bit closer than the average distance between the two at 886 million miles. Saturn’s oppositions are about 378 Earth-days apart, so it reaches opposition nearly every Earth-year.

⭐ What will Saturn look like at opposition?
During opposition, Saturn will be at its largest and brightest all year. It’s the seventh-brightest natural object in the solar system, and brighter than the vast majority of stars in the night sky, but it still looks very similar to a star when viewed with the naked eye. Since Saturn will be fully illuminated by the Sun, it will glow like a gold-white beacon in the sky. Though it will be at it’s closest and easiest for us to see from Earth, it will still appear round, and you will not be able to see any rings or other features unless you use a powerful pair of binoculars or a good telescope.

⭐ When and where is the best time and place to view Saturn at opposition?
Saturn will rise in the east at sunset and will be visible all night during opposition on October 4th. Opposition is officially at 5am, but no need to get up that early! The view will still be at its best on the evenings of October 3rd and 4th, no matter what time you view it. But for the clearest view, wait until around 1am when Saturn is highest in the sky and Earth’s atmosphere is least likely to affect its clarity. To locate Saturn, look within the constellation Cetus (the sea monster or whale) – Saturn will be a little higher than the star Iota Ceti (the tail of Cetus) and will display a steady, gold-ish glow.

You will be able to see Saturn with the naked eye, but you will be able to see a fuzzy peanut-shape using binoculars with at least 15x to 20x magnification, and a telescope with a 75mm aperture with 25x to 30x magnification will allow you to see the planet shape and rings more clearly. Unfortunately, Saturn is only tilted about 7.5 degrees relative to Earth right now so the rings will appear nearly head-on, making them more difficult to see.

The Moon will be a waning crescent, with about 40% of its surface illuminated, so its light may interfere a little with your view, but you can position yourself next to a building or tree to block out some of the moonglow. If you miss seeing Saturn at opposition, you’ll still get plenty of opportunity to see the planet as it remains visible in the night sky until March of next year.

Good luck and happy viewing!
📷 1: Positions of Saturn, Earth, and the Sun when Saturn is at opposition. Via Lowell Observatory
📷 2: During opposition, Saturn will be visible near constellation Ceti. Look up in the SW sky around midnight to locate the bright planet. Modified from Stellarium.

09/29/2026

Playing This Week at the Science Dome!

👽 Exo: Are We Alone? - Wednesday, September 30th, 5:15pm
Today we know of thousands of exoplanets — planets located outside our Solar System — that offer valuable information about our own planet, its origins and life on Earth. We’re on the cusp of making some fascinating discoveries. But how will they change our lives?

🎶 Pink Floyd - Wednesday, September 30th, 6:30pm
Each song has a different theme; some futuristically looking forward and some a retro acknowledgment to Pink Floyd’s visual history, all relating to a time and space experience, embracing up to the minute technology that only a Planetarium can offer.

🌎 Birth of Planet Earth - Friday, October 2nd, 6pm
How did Earth become a living planet in the wake of our solar system's violent birth? What does its history tell us about our chances of finding other worlds that are truly Earth-like?

👑 Cosmic Legacy: Tribute to Queen - Friday, October 2nd, 7:15pm
On-screen visuals guide you on a hypnotic journey that inspires nostalgia with hits like ‘Bohemian Rhapsody’, ‘We Will Rock You’ and ‘Love of My Life’. Celebrate Queen’s cosmic legacy with music and visuals that will take you to galaxies of emotions!

🎙️ Global Soundscapes - Saturday, October 3rd, 3:30pm
Listen...can you hear that? It’s the sound of the Earth! Global Soundscapes takes you on a sound safari to explore the health of our planet...with your ears. With Global Soundscapes’ unique format—combining giant screen images, surround sound, and live presentation—you’ll hear the Earth in a whole new way!

🌈 Aurorae: Lights of Wonder - Saturday, October 3rd, 4:45pm
The aurora is the greatest wonder a human can experience in nature. For the first time ever, you can experience an actual auroral substorm in real-time, high-resolution fulldome video, captured by astrophotographer O-Cheol Kwon in Yellowknife, Northwest Territories, Canada.

🎶 Pink Floyd - Saturday, October 3rd, 6pm

Each all-ages public show features a 30-minute live night sky talk in the planetarium PLUS a 30-minute fulldome video (except for music shows, which do not include a live talk).

$8 general admission (except for music shows, which are $15)
Pierce College Students are free with ID

09/22/2026

Playing This Week at the Science Dome!

💥 Spark: The Universe in Us - Wednesday, September 23rd, 5:15pm
Travel inside a giant star nearing the end of its life, witness stellar corpses colliding, and experience the quiet demise of a Sun-like star.

🌈 Aurorae: Lights of Wonder (sensory-friendly version) - Wednesday, September 23rd, 6:30pm
For the first time ever, you can experience an actual auroral substorm in real-time, high-resolution fulldome video, captured by astrophotographer O-Cheol Kwon in Yellowknife, Northwest Territories, Canada.

📡 Messengers of Time and Space - Friday, September 25th, 6pm
Messengers of Time and Space is a stunning visual and educational experience that leads you on a journey through the dynamic Universe during a night of observing at the International Gemini Observatory.

🎶 Pink Floyd - Friday, September 25th, 7:15pm
Each song has a different theme; some futuristically looking forward and some a retro acknowledgment to Pink Floyd’s visual history, all relating to a time and space experience, embracing up to the minute technology that only a Planetarium can offer.

🌎 Nacimiento del Planeta Tierra - Sábado 26 de septiembre, 11:30am
La película utiliza visualizaciones avanzadas basadas en datos y con calidad cinematográfica para explorar algunas de las preguntas más importantes de la ciencia actual: ¿Cómo se convirtió la Tierra en un planeta con vida después del violento nacimiento de nuestro sistema solar? ¿Qué nos dice su historia sobre nuestras probabilidades de encontrar otros mundos que sean verdaderamente similares a la Tierra?

🎤 Global Soundscapes - Saturday, September 26th, 3:30pm
Listen...can you hear that? It’s the sound of the Earth! Global Soundscapes takes you on a sound safari to explore the health of our planet...with your ears.

🌋 Dynamic Earth - Saturday, September 26th, 4:45pm
The award-winning Dynamic Earth explores the inner workings of Earth’s great life support system: the global climate.

👑 Cosmic Legacy: Tribute to Queen - Saturday, September 26th, 6pm
On-screen visuals guide you on a hypnotic journey that inspires nostalgia with hits like ‘Bohemian Rhapsody’, ‘We Will Rock You’ and ‘Love of My Life’.

Each all-ages public show features a 30-minute live night sky talk in the planetarium PLUS a 30-minute fulldome video (except for music shows, which do not include a live talk).

$8 general admission (except for music shows, which are $15)
Pierce College Students are free with ID

09/22/2026

Is There Water on the Moon?

Hundreds of years ago, astronomers believed the dark patches on the Moon’s surface were vast oceans of water and decided to call them maria (Latin for “seas”). Unfortunately, the dark patches turned out to be regions of dark volcanic rock (basalt) that were completely devoid of liquid water. But, is it possible the Moon has water hidden somewhere in the dark? Read on to find out!

⭐ Is there water on the Moon?
Yes! However, it is not liquid water like much of ours here on Earth. Most of it is trapped in water ice, but some water molecules have been discovered within rock and glass fragments of lunar soil as well. The idea that water ice may exist in shadowed regions of the Moon was first introduced by theoretical physicist Kenneth Watson in 1961, but it wasn’t confirmed for certain until data from the Moon Mineralogy Mapper on India’s Chandrayaan-1 spacecraft revealed surface-exposed water ice in shadowed polar craters in 2018.

Most of the water ice on the Moon is located inside permanently shadowed regions (PSRs), which are typically located within large, deep craters at the north and south poles where sunlight never reaches and the temperature is always below -250° F. The South Pole contains the largest reserves of water ice primarily because it is home to much larger, deeper, and older impact craters than the North Pole. Since water is the most valuable resource for long-term space travel, future lunar missions like NASA’s Artemis and VIPER Rover, China’s Chang’e, and private commercial landers are targeting the South Pole in the hopes of mining the water ice. Scientists hope that the water can be used for more than just drinking, since water molecules can be split into hydrogen used for rocket fuel and oxygen used to breathe, for example.

Water molecules have also been found in sunlit areas of the Moon, trapped within components of the lunar soil that is widely spread across the Moon's surface. In 2019, NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) confirmed the presence of water molecules in Clavius Crater; a huge, sunlit crater in the Moon’s southern hemisphere. The molecules appear to be trapped within microscopic glass beads that formed when the extreme heat of a micrometeorite impact melted the lunar soil. But the water molecules are so spread out that even the Sahara Desert contains more than 100 times the amount of water found in the lunar soil! It's also possible that there is liquid water deep below the surface of the Moon, but so far that’s just a theory.

Scientists estimate that there is up to 1 billion metric tons of ice frozen at the lunar poles, and another 300 billion tons trapped within the regolith. Though that may sound like a lot, the Moon actually has 4.6 million times less water than Earth! For example, if all of Earth’s water could somehow fit within an Olympic-sized swimming pool, the total amount of the Moon’s water would only equal about two teaspoons of water, using the same scale.

⭐ Where did the water come from?
Like Earth’s water supply, the Moon derived its water primarily from impacts with carbonaceous chondrites, which are primitive, water-rich asteroids that can contain up to 22% water and organic compounds. Most of the water found in carbonaceous chondrites is trapped within hydrated minerals like serpentine and clays. The intense heat of chondrite impacts on the Moon released water v***r from within the hydrated minerals. Most of the water v***r was released into space because the Moon has a very thin atmosphere that cannot trap the water like Earth’s atmosphere can. But, some of the water v***r released in the PSRs froze into water ice instead.

Fun fact: Serpentinite is a common rock on Earth that contains up to 13% water by weight and is the primary driver of introducing water into Earth’s mantle via subduction, which is why we have melted rock that erupts from volcanoes like those in the Cascades!

⭐ Can humans use the water?
The Moon does have enough water to potentially sustain a small lunar base and fuel deep-space missions, but it will not be easy to extract! Space agencies are developing the technology as we speak, but we’re still probably at least a decade away from figuring out how to mine the water on a large scale. The leading strategy involves placing giant tents or mirrors over the polar ice and catching the heated/v***rized water in containers.

The most impactful way humans can use lunar water is as a sort of gas station. Hydrogen fuel can be made by splitting water molecules into hydrogen and oxygen components, which can power deep-space spacecraft launching from lunar bases. With an off-Earth gas station and low-gravity launching location, sending humans farther into space would be much easier.

Would you drink a glass of Moon water, given the chance?

📷: This map, based on data obtained by NASA's SOFIA aircraft, shows water distribution across the surface of the Moon. Via NASA

09/17/2026

It's that time of year again! Our hugely popular Halloween-themed children's planetarium show, Haunted Night Sky, will play every Saturday from September 26th to October 31st! These shows do sell out, so be sure to get your tickets early!

You are formally invited to this year's Haunted Night Sky! Come one and all to Zob the Alien's Halloween Party! This party will feature travel to distant skies, new friends, and of course - candy! While costumes are not required to attend, we encourage you to show your Halloween spirit by dressing up. We hope to see you there!

This live and interactive program involves hands-on activities and audience participation. It is designed for our youngest visitors. However, it does get dark in the planetarium and it is not recommended for children younger than 3.

Tickets are $8 and can be purchased here: https://piercecollegedome.ludus.com/index.php?sections=events

09/09/2026

Last week, we wrote about Venus and the reason it rotates so slowly, including how the planet is partially tidally locked. The Moon, as you may know, is completely tidally locked, meaning that we only ever see one side of the Moon from here on Earth. This week, we’re going to dive a little deeper into why we only see one side of the Moon, what the other side of the Moon looks like and why, and how common it is for a celestial object to be tidally locked with another object!

⭐ Why do we see only one side of the Moon from Earth?
We see only the “near side” of the Moon because it rotates on its axis in the exact same amount of time it takes to orbit Earth, due to something called tidal locking. Tidal locking (sometimes called synchronous tidal locking) is a gravitational phenomenon that can be difficult to picture, but it’s sort of like when you spin in circles with your friend while you’re holding hands and facing each other. You’re both spinning and completing individual rotations, but you stay facing each other because your orbital period (the time it takes to complete one full circle around you and your friend’s pivot point) exactly matches your rotation period (the time it takes your body to rotate 360°).

A larger, more massive object will pull harder on the near side of a less-massive orbiting object, which stretches it into an almost egg-like, oblong shape called a tidal bulge. The smaller object will likely start out spinning faster than it orbits, so the gravitational bulge will be slightly out of alignment with the gravitational pull of the larger object. The gravitational pull on the mis-aligned tidal bulge acts as a brake that slowly slows down the orbiting object’s spin until its rotational period matches the orbital period, at which point the rotation stays locked. So, just like spinning with your friend, we always see the same face of the Moon, even though it is rotating.

⭐ If you were on the Moon, would you always see the same side of Earth?
No, you would see all sides of Earth as it rotates because it is spinning relatively faster on its own axis. What’s really cool though is that, from the surface of the Moon, Earth would never rise or set – it would remain in the same position in the sky at all times because your viewpoint from the Moon is rotating at the same exact speed that the Moon is orbiting Earth. You would also see Earth go through phases like we see with the Moon, such as a “crescent Earth”, “new Earth”, or “full Earth”!

⭐ Is there such thing as the “dark side” of the Moon?
Sorry, Pink Floyd, but there is no “dark side” of the Moon. There is a far side though, and people historically thought it was dark because the far side is hidden from our view and facing the dark blackness of space. In reality, both sides of the Moon receive exactly the same amount of sunlight and, when the Moon is in a new moon phase, the far side is fully illuminated by the Sun.

⭐ Why does the far side of the Moon look different from the near side?
If you’ve ever seen images or maps that show both sides of the Moon side-by-side, you may have noticed that the near side has larger patches of relatively smooth surface and fewer craters. This is primarily because of crustal asymmetry that developed as the Moon was forming and cooling. The Moon formed from the debris left over from the collision of a large object and Earth about 4.3 billion years ago, when the solar system was still pretty young. Without going into too much detail, that process left the near side of the Moon with a thinner, hotter crust while the far side had a thicker, cooler crust. The near side had more volcanic eruptions that erased many of the craters that impacted the Moon, resulting in a smoother surface with large mare; the large patches of dark-colored volcanic rock. The far side’s thicker and cooler crust preserved the impact craters without overprinting them with large volcanic eruptions.

⭐ Are any other objects in our solar system tidally locked?
Tidal locking is actually very common! In fact, every moon in our solar system that is massive and close enough to its parent planet is tidally locked. Notable pairings include:

▪️Mars and its moons, Phobos and Deimos
▪️Jupiter and its four Galilean moons – Io, Europa, Ganymede, Callisto
▪️Saturn and its moon Titan, Enceladus, Mimas, etc.
▪️Uranus and its major moons – Ariel, Umbriel, Titania, Oberon
▪️Neptune and its moon, Triton

And though it is no longer considered a planet, Pluto is actually mutually tidally locked to its moon, Charon. Pluto and Charon are relatively close in mass, so both objects act as gravitational brakes on each other.

While we’re on the topic of the “dark side of the Moon” though, we want to remind you to check out our Pink Floyd show at the Dome! It features awesome visuals set to the entire Dark Side of the Moon album and is one of our favorite shows we’ve ever had! Scroll down to the Pink Floyd section for more information and a link to purchase tickets!

📷: The near side of the Moon (left) and far side of the Moon (right). Via NASA LRO/Jatan Mehta.
📽️: An animation showing the difference in view before and after Earth-Moon tidal locking. Via Vi Nguyen, NASA Goddard Space Flight Center.

09/08/2026

Playing This Week at the Science Dome!

🌎 Habitat Earth - Wednesday, September 9th, 5:15pm
Through stunning visualizations of the natural world, dive below the ocean’s surface to explore the dynamic relationships found in kelp forest ecosystems, travel beneath the forest floor to see how Earth’s tallest trees rely on tiny fungi to survive, and journey to new heights to witness the intricate intersection between human and ecological networks.

🌈 Spectroscopy: A Deep Dive Live Talk - Wednesday, September 9th, 6:30pm
Discover how astronomers use light to uncover the universe's hidden details - from the composition of distant stars to movements of galaxies - all without having to leave Earth. This show is an introduction to spectroscopy and the physical properties underlying it that requires no prior background knowledge.

👩‍🚀 Mars: The Ultimate Voyage - Friday, September 11th, 6pm
On a two year journey to Mars astronauts will face extraordinary challenges—long distance, a closed environment, isolation, altered gravity, radiation. What will it take to get astronauts to Mars—and back—safely?

👑 Cosmic Legacy: Tribute to Queen - Friday, September 11th, 7:15pm
Get ready to take off into an unlimited sound universe! Queen, the band that shook the cosmos with its music, leaves us a cosmic legacy that pierces the soul. On-screen visuals guide you on a hypnotic journey that inspires nostalgia with hits like ‘Bohemian Rhapsody’, ‘We Will Rock You’ and ‘Love of My Life’.

🎤 Global Soundscapes - Saturday, September 12th, 3:30pm
Listen...can you hear that? It’s the sound of the Earth! Global Soundscapes takes you on a sound safari to explore the health of our planet...with your ears. Travel the globe with scientists to investigate the spectacular soundscapes of Costa Rica’s rainforests, Hawaii’s coral reefs, and Mongolia’s vast grasslands.

🌊 Wayfinders: Waves, Winds, and Stars - Saturday, September 12th, 4:45pm
In Wayfinders: Waves, Winds, and Stars, learn how to read the stars and interpret the wind and waves as we follow the story of Hawaii’s Polynesian Voyaging Society and their efforts to recover the nearly lost techniques of traditional Polynesian navigation aboard the double-hulled canoe Hōkūleʻa.

🎶 Pink Floyd - Saturday, September 12th, 6pm
Each song has a different theme; some futuristically looking forward and some a retro acknowledgment to Pink Floyd’s visual history, all relating to a time and space experience, embracing up to the minute technology that only a Planetarium can offer. A truly immersive and all-encompassing surround sound and visual treat that will transcend reality and take you way beyond the realms of 2D experience.

Each all-ages public show features a 30-minute live night sky talk in the planetarium PLUS a 30-minute fulldome video (except for music shows, which do not include a live talk).

$8 general admission (except for music shows, which are $15)
Pierce College Students are free with ID

09/02/2026

Have you ever had a bad day that feels a lot longer than usual? How about a day that lasts 243 days? If you were on Venus, that’s how long it would take to finish just one planetary rotation, called a sidereal day! August 31st was the 243rd day on Earth, so Venus just now completed one sidereal day (though technically, it only takes about 117 Earth days for Venus to complete a full day-and-night cycle). So why does it take so long for Venus to complete a rotation, compared to Earth, and do the other planets have similarly off-set days to Earth? Read on to find out!

⭐ Why does it take Venus so long to complete one rotation?
The biggest reasons Venus rotates so slowly is because of tidal locking and Venus’ very fast-moving atmosphere. When a large massive object (the Sun) unevenly pulls on an orbiting object (Venus), it creates enough gravitational friction that the less massive object’s rotation is slowed or stopped, leaving the same side always facing the more massive object. That’s what would be the case for Venus, if not for its atmosphere and the atmospheric bulge that the Sun pulls in the opposite direction of the rest of the planet.

Venus has an incredibly thick atmosphere (about 90x “heavier” than Earth’s!), made mostly of carbon dioxide and nitrogen gasses. Near the surface, those gasses are compressed so extremely that they behave almost like a liquid gas, making Venus’ atmosphere extremely dense (the densest of all rocky planets). Continuous heating and cooling from the Sun causes much of the atmospheric mass to pile up on one side of the planet, creating an atmospheric tidal bulge that the Sun pulls on, which drives fast winds that drag along Venus and generate just enough friction to cancel out the tidal locking. So, Venus rotates very slowly but it isn’t technically tidally locked, like our Moon, for example.

Fun fact: Venus actually rotates “backwards”, compared to most other planets in our solar system (except for Uranus). Scientists believe this could be due to the atmospheric tug-of-war, a giant collision in Venus’ past, or some combination of the two.

⭐ How fast do other planets in our solar system rotate, compared to Earth?
Compared to Earth’s 24-hour day, the rotational speeds of other planets in our solar system are generally split into the slower-spinning planets (the rocky inner planets) and the faster-spinning planets (the gas and ice giants). For a single rotation, it takes each planet about:

Mercury: 59 Earth days
Venus: 243 Earth days
Earth: 1 Earth day/24 Earth hours
Mars: 1.025 Earth days/24.6 Earth hours
Jupiter: 9.9 Earth hours
Saturn: 10.7 Earth hours
Uranus: 17.2 Earth hours
Neptune: 16.1 Earth hours

If we compared the time required to complete a rotation against an Earth year beginning on January 1st at 12am, each planet would complete a rotation around:

Mercury: March 1st, midnight
Venus: August 31st, midnight
Earth: January 2nd, midnight
Mars: January 2nd, midnight
Jupiter: January 1st, 9:54am
Saturn: January 1st, 10:42am
Uranus: January 1st, 5:12pm
Neptune: January 1st, 4:06pm

⭐ Why do gas and ice giant rotate so much faster than the inner rocky planets?
There are a few reasons for the dramatic difference in rotational speeds between our outer and inner planets.

▪️Size and mass difference
The outer planets formed far away from the Sun and were able to accumulate greater ice, rock, and gas matter very quickly, making them very large and massive, whereas the inner planets were restricted to accreting rock and metals like iron and nickel, which limited their final size.

▪️Conservation of angular momentum
Have you ever noticed how an ice skater can spin faster when their arms are pulled in close to their body? That’s because they are reducing their moment of inertia, which forces their rotational speed to increase to conserve angular momentum. The same thing happened with the outer planets – the gas and rock that collapsed inward under the pull of the protoplanet’s gravity concentrated the mass into a dense mass, causing its rotational speed to increase dramatically.

▪️The Sun’s gravitational grip
The inner planets are much closer to the Sun and are therefore highly influenced by its gravitational pull, which kind of “steals” the rotational energy from the planet and makes it rotate much slower. Outer planets are so far away from the Sun that they are not as easily influenced by the Sun’s gravity, so they have mostly maintained the quick spins they developed during formation.

⭐ Why do planets rotate at all?
During the formation of our solar system, a massive cloud of gas and dust was kind of hanging out in space. The area where the gas and dust were most dense is where our star began forming. As the young star pulled more and more material towards it, the material began to spin rapidly, like water spinning down a drain. This large-scale rotation was conserved as each planet formed, resulting in individual rotations for each planet. Since all material in the solar system was originally spinning in the same direction, (most) planets also spin in that direction, except for the two whose rotations have been disrupted in some way so that their rotational direction reversed.

Here's hoping (at least your bad) days go by a bit faster than those on Venus!

📷: Rotational speeds and length of sidereal days of all eight planets in the solar system. Via NASA/NOAA

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