Science

Saturn’s New Moons | Update 23.2

Run Steam to download Update 23.2, or buy Universe Sandbox via our website or the Steam Store.

Introducing the new Moon Champion of the Solar System, with a total of 82 known moons, it’s the great ringed gas giant Saturn!

Take a tour through the discoveries of Saturn’s moons, from the first discovered moon, Titan, in 1655, to the latest discovery of 20 new moons in October 2019:

Home > Guides > Science > History of Saturn’s Moons

With 82 moons, Saturn now has the most known moons, surpassing the previous record holder Jupiter and its 79 known moons.

This update also includes a refresh of our database and Saturn simulations to add its new moons, plus a few smaller fixes and improvements.

Check out a full list of What’s New in Update 23.2

 


Dark Matter & Galaxies in Universe Sandbox

You may notice that our new galaxy model (added in Update 23, released on June 25, 2019) no longer includes those bright red dots. The dots were how we represented dark matter in the old galaxy model (pre-Update 23), but we’ve decided not to include dark matter in the new model, for a number of reasons.

Short Explanation

Here’s the TL;DR explanation of why we removed dark matter in our new galaxy model:

Dark matter is a theoretical particle proposed to explain the unexpected motion of stars in galaxies. Due to performance constraints, our simplified galaxy dynamics model can’t simulate these complex orbits, so we’ve decided to remove dark matter from our simulations for now.

If you’re looking for a more in-depth explanation, keep reading!


Left: Spiral galaxy with dark matter (pre-Update 23). Right: Spiral galaxy in Update 23.

What is dark matter?

No one knows for sure what dark matter is, or even if it exists! But a number of different observations of our universe have revealed stars and galaxies moving under the gravitational influence of more mass than we can see. This hints at the presence of some kind of matter that affects stars and other bodies via gravity, but that can’t be observed directly. This proposed “dark matter” doesn’t produce light, but it also doesn’t block it, or we would be able to see it silhouetted against brighter stars and galaxies in the background (like we can see dust in the Milky Way).

We don’t know of a type of particle that has mass but that doesn’t interact with light, but a few ideas have been proposed. It may be a new type of particle that we haven’t discovered yet, and several ongoing experiments are trying to directly detect such a particle. Some scientists argue that dark matter does not exist at all, and that the “missing mass” in astronomical observations simply indicates that our mathematical description of gravity is not yet complete.

What does this have to do with galaxies?

Spiral galaxies were one of the first examples of the missing mass problem. Astronomers discovered the problem while calculating the “rotation curve” for these galaxies: a plot of the velocity of a star orbiting in the galaxy, versus the distance of that star to the center of the galaxy. The speed at which an object orbits in space is related to the mass of everything inside its orbit, and the distance to the center of the orbit. In the Solar System, nearly all of the mass inside a planet’s orbit is made up of the mass of the Sun, so the difference in speeds of planet orbits is due mostly to their distance from the Sun. Thus, the rotation curve of planets in the Solar System starts with the high speed of Mercury’s orbit, and then drops off as you move outwards to Venus, Earth, and the rest of the planets.

But in a galaxy, most of the mass is distributed among the stars that make up the galaxy, so stars farther from the center are orbiting more mass than stars closer in. We can estimate the distribution of mass based on the stars that we see, and predict a slightly more complicated curve: First, the velocities of orbiting stars should increase as you move away from the center, as more and more mass is enclosed by the orbit. But eventually, the extra mass inside the orbit won’t be enough to make up for the increased distance from the center, and the velocities will start to decrease again. The predicted curve has a sort of hump shape, with a long, decreasing tail.

Rotation curve of the galaxy M33. The yellow and blue dots indicate the data, while the dashed line represents the curve you would expect based on the amount of visible mass in the galaxy. Instead, the velocity increases with distance, indicating that more mass is present than we can see. Credit: Mario De Leo

But when astronomers actually measure these velocities and create rotation curves of spiral galaxies, the curves don’t drop off with distance. Instead, the velocities get faster and faster as you move outwards, with stars on the outer edges moving so fast that you would expect them to fly off, pulling the galaxy apart. One explanation for this discrepancy is that some kind of unseen mass (“dark matter”) may be present in spiral galaxies, keeping those stars gravitationally bound to the galaxy despite their high speeds.

Dark matter in Universe Sandbox

Since Universe Sandbox is at its core a gravity simulator, we tried to show the influence of dark matter in our previous galaxy model. For a given galaxy, we would calculate the distribution of dark matter that we would expect based on real observations of galaxy rotation curves. Specifically, we used what’s called the Navarro-Frenk-White (NFW) profile, after the astronomers who identified the distribution. We simulated the dark matter as points of mass scattered through the galaxy, and displayed them as bright red dots (because dark matter is invisible, we wanted to make it clear that we weren’t showing what dark matter “really” looks like!).

This model would give the “right” distribution of dark matter in a galaxy, but it couldn’t reproduce the most important feature of dark matter in galaxies: the rotation curve. This is because of the way that galaxy simulation works in Universe Sandbox.

How galaxies are simulated in Universe Sandbox

In both the old and the new versions of our galaxy model, we represent the galaxy as a collection of non-attracting particles orbiting a single attracting body, the black hole at the center. Each particle represents a cloud of gas, dust, and stars, which we call a nebula. This means that to our physics engine, the nebulae have zero mass, and the only gravity in the galaxy comes from the black hole.

But wait, earlier we said that the mass in a galaxy is spread out among all the stars in the galaxy, instead of being concentrated in the center like the Solar System. Why don’t we make all the nebulae into attracting particles? This would certainly make the motion of the galaxy more accurate, but in any gravity simulator, the number of attracting particles significantly affects performance. (You can see this for yourself by opening a simulation with a lot of attracting bodies, like Earth & 50 Moons.) To make galaxies look as good as they do, we need to use hundreds or even thousands of nebulae. A simulation with a thousand attracting particles would run extremely slowly even on a very powerful gaming computer. So instead, we used a simplified model of non-attracting nebulae orbiting an attracting black hole.

In the old version of galaxies, nebulae moved on circular orbits around the black hole, and the initial structure of a galaxy, whether it was a spiral or elliptical, would quickly lose its distinctive shape. In our upgraded version, nebulae are given specific orbits to allow the galaxy to hold its shape over time. The presence of another attracting body besides the black hole will pull the galaxy out of shape. (You can watch this happen in any galaxy collision simulation, or just by adding multiple galaxies to one of your own simulations!) During the development of this upgrade, we realized that adding attracting particles to represent dark matter would make it difficult to maintain the shape of spiral and elliptical galaxies for the same reason.

Because we are using a simplified galaxy model, we can’t reproduce the galaxy rotation curves we would expect either with or without dark matter. Instead, the rotation curves for our galaxies look more like the Solar System’s: the velocities of the nebulae drop off quickly as you move outwards from the center. Since this model can’t demonstrate the major effect of dark matter in galaxies, we decided to remove it for now.

We are hoping that a future version of galaxies will use computational methods like Smoothed-Particle Hydrodynamics (SPH) that will allow us to simulate hundreds to thousands of attracting nebulae orbiting the galaxy. This even more accurate model will be able to produce realistic galaxy rotation curves, and at that point, we’ll add dark matter back in so users can see its observable effect. In the meantime, we hope you enjoy our improved, interactive galaxy model!

 


Universe Sandbox Takes Off in China

The Wandering Earth


Have you heard of the sci-fi blockbuster The Wandering Earth? While it has had modest success with a limited release in the United States, it is now China’s second-highest-grossing film of all time with over $679 million in domestic box office sales.

The screenplay is based on a story by Liu Cixin, a renown Chinese sci-fi author who has popularized the genre with his award-winning stories, including the novel The Three-Body Problem (which also has a movie adaptation in the works and received praise from Barack Obama).

Simulating a Disaster Film


Earth being ripped apart by Jupiter’s tidal forces in Universe Sandbox.

Critics say The Wandering Earth often falls victim to the trappings of disaster films (overblown CGI, heavy-handed sentimentality, etc.), but what excites us is the scenario that plays out in the film.

To us, the plot summary reads like a description of a simulation in a not-too-distant version of Universe Sandbox: [SPOILERS] In the future, Sun evolves into red giant and threatens Earth habitability → Gigantic thrusters are attached to Earth (you better believe this fits well into our development plans) → Earth is propelled farther from the Sun and freezes over → Tidal forces from Jupiter wreak havoc as Earth approaches the gas giant and prepares for collision → A GIF of this terribly interesting disaster is captured and the simulation is shared to Steam Workshop… oh wait that part wasn’t in the film.

Of course, we weren’t the only ones to see this potential. Video creators in China familiar with Universe Sandbox immediately got to work simulating the events of the film.

Here are a couple of the more popular ones that we’re aware of:

 

Sales Boost

The news of the rising popularity of these videos in China was shared with us by our proofreader for the Chinese language in Universe Sandbox. And sure enough, this correlated with a sharp rise in Universe Sandbox sales in China that we had noticed a week before, along with an influx of Steam reviews written in Chinese (some of which mentioned The Wandering Earth explicitly).

The overlap with Steam’s Lunar New Year sale meant that, for the first two weeks in February, Universe Sandbox copies sold in China made up 50% of our total sales on Steam. Compare this to the previous two weeks, when Chinese sales accounted for only 7% of total sales.

 

Translating Chinese

Needless to say, we’re extremely grateful for the exposure brought to us by The Wandering Earth and the content creators who used Universe Sandbox to explore its premise. It’s also not hard to imagine that our support for Chinese in Universe Sandbox, which we added last summer, also played a part in making it more accessible and appealing to Chinese players. That said, we don’t want to overlook some criticism we have received about the current Chinese translations. Some reviewers noted that, while it’s appreciated that there is support for Chinese, the translations themselves could be vastly improved.

As with all of the languages we support, we currently rely on community volunteers to suggest improved translations and vote on the best ones. We have contributors now, including a proofreader who approves the best translations, but this is a big project — we are often changing and adding text, and we have no way ourselves to review the quality of the translations. We hope that as the community grows, we have more community members able to help improve these translations.

Want to help translate? Just click “Help Translate” on the Home panel and follow the instructions. Learn more

Want to be a proofreader that approves translations? Let us know!

 

 


Universe Sandbox at the American Astronomical Society Conference

Super Bowl of Astronomy

In early January we gathered some of our team in Seattle, Washington to show off Universe Sandbox at the 233rd meetup of the American Astronomical Society (AAS).

We’ve attended other conferences before that focus on video games, like PAX, but AAS gave us an opportunity to show Universe Sandbox to a different crowd. If you are a researcher, educator, science journalist, or student in the world of astronomy, then AAS is the go-to conference, what some call the “Super Bowl of Astronomy.” And while the government shutdown meant that hundreds of NASA employees who planned on attending couldn’t go, there was still plenty of folk there who had never heard of Universe Sandbox and wanted to learn more.

 

Come for the Collisions, Stay for the Accurate Mass Loss

Drawing people into our booth was helped a bit by two gigantic TVs showing off some of the usual Universe Sandbox scenarios — you know the ones: Earth melting, stars exploding, moons ripping apart under massive tidal stress.

But what made many attendees stick around and talk to us was the fact that what we were showing not only looked great, but it was also based in science. Universe Sandbox: Come for the fiery collisions, stay for the accurate mass loss when Ceres makes a near pass of a white dwarf!

 

Communicating with Universe Sandbox

In talking to AAS attendees, we hoped to show the potential for using Universe Sandbox for education and visualizations. While most Universe Sandbox players know and appreciate how useful it can be as an educational tool, we want to make sure it gets used in actual classrooms. We believe Universe Sandbox makes it quick and easy to demonstrate astronomy and physics concepts with intuitive and interactive experiments. But don’t take our word for it — here’s astronomy YouTuber Scott Manley with a similar message.

And beyond the classroom, it’s just as quick and easy to use Universe Sandbox for creating visualizations for research, lectures, and articles. There are more sophisticated tools for gathering data with the accuracy needed for research, but there’s nothing quite as convenient as Universe Sandbox for then using the data to create a visual representation, as shown here with the discovery of exoplanets around our nearby star Wolf 1061.

If you’re an educator, a researcher, or are otherwise curious how you can use Universe Sandbox for science communication, please get in touch!

 


New Year, New Limits of our Solar System for New Horizons

Happy New Year!

While we celebrate one more trip of our beautiful planet around the Sun, the spacecraft New Horizons sets a record for traveling to the most distant object in our Solar System ever visited, 2014 MU69, nicknamed “Ultima Thule.” This object is currently 1 billion miles beyond Pluto, or more than 43 AU from the Sun, which means it is more than 43 times the distance between the Earth and the Sun. New Horizons is expected to make its closest approach to Ultima Thule shortly after midnight EST January 1, 2019.

Check out the flyby in Universe Sandbox:

Home > Open > New Horizons Ultima Thule Encounter in 2019

 

New Limits for New Horizons

After the record-setting 2015 flyby of Pluto and its moons, the New Horizons spacecraft continued its journey through the outer reaches of the Solar System. In that same year, NASA selected a new target for New Horizons to observe: a Kuiper Belt object discovered by the Hubble Space Telescope the year earlier, known as 2014 MU69. Unofficially named Ultima Thule in 2018 based on a public vote, this object will be the most distant ever visited by a human spacecraft (breaking the record New Horizons itself set when it flew past Pluto).

The team says it hopes to set a new target for New Horizons once it passes Ultima Thule. With plenty of remaining fuel and equipment and instruments that remain in good condition, New Horizons is all set to head toward another distant object in the Kuiper Belt, arriving sometime in the 2020s, the team said.

 

Simulation Limitations

Simulations in Universe Sandbox are not perfect representations of reality. Rather, they’re meant to provide a visual — and as a result, a more intuitive understanding — of what is happening farther away than we can see or even imagine. With that in mind, there are a couple of limitations currently in this simulation:

1 –  Trajectory

The trajectory shown is according to the NASA Jet Propulsion Laboratory’s orbital predictions as of September 2018. Additional maneuvering with thruster burns is expected, which would change the final trajectory. New Horizons will make an approach much closer than is represented in the simulation: it should pass about 3,500 km from 2014 MU69. Once actual trajectories have been recorded, we will update the simulation.

2 – Shape

Previous observations show that 2014 MU69 is likely not spherical, but rather cigar-shaped. Researchers suspect that Ultima Thule may even be two separate bodies that are either orbiting very closely as a binary or actually touching each other, which is called a contact binary. We should know more once New Horizons sends back data from its flyby! Right now, Ultima Thule is represented in Universe Sandbox as just a single, spherical body.

 

Other Far Out Objects

Update 22.1 of Universe Sandbox added three other simulations that feature very distant objects in our Solar System.

 

1 – Voyagers 1 & 2 in Interstellar Space

In November 2018, more than 40 years after its launch, and long since trips past Jupiter, Saturn, Uranus, and Neptune, the Voyager 2 probe entered interstellar space. It now joins its twin, Voyager 1, in exploring beyond our Solar System. They are expected to continue to send back data until they run out of power in 2025.

Home > Open > Voyagers 1 & 2 Start 2019 Outside the Solar System

 

2 – 2018 VG18, “Farout”

On December 17, 2018, astronomers announced the discovery of the most distant known object in the Solar System, 2018 VG18. Nicknamed “Farout” (can you guess why they chose that name?), the trans-Neptunian object is currently around 120 AU (1 AU is the distance from the Sun to the Earth) from the Sun. While this object is the most distant ever observed, there are other known objects, like Sedna and the Goblin (see below), that have orbits that take them much farther from the Sun.

Farout’s orbit shown in this simulation is a preliminary estimate; its distance means it will take years of observation before its precise orbit is known.

Home > Open > 2018 VG18: The Most Distant Object in the Solar System

 

3 – 2015 TG387, “The Goblin”

On October 1, 2018, astronomers announced the discovery of the trans-Neptunian object 2015 TG387, which they nicknamed “The Goblin.” It was observed at about 80 AU from the Sun, but because of its extremely elongated orbit, it likely travels to a distance of more than 2300 AU at its farthest point.

Home > Open > 2015 TG387: A Goblin at the Edge of the Solar System

 


The Extremes of Our Solar System | Update 21.3

Run Steam to download Update 21.3, or buy Universe Sandbox ² via our website or the Steam Store.

This is a small update that features a new Parker Solar Probe model and new simulations exploring extremes in our Solar System:

Skim past the Sun with the Parker Solar Probe. The probe was launched in August and now has 24 trips around the Sun planned for its 7-year mission. Each year its orbit will take it closer to the Sun as its instruments capture data that will help us better understand our resident star. Its closest approach will bring it within 8.86 solar radii, or 3.83 million miles, of the Sun’s surface, more than 7 times closer than any previous spacecraft.

Home > Open > The Parker Solar Probe
Home > Open > The Parker Solar Probe’s Closest Approach to the Sun
Add > Objects > Parker Solar Probe

And ride along with New Horizons as it continues through the far reaches of our Solar System past Ultima Thule. After the probe’s flyby of Pluto and its moons in 2015, NASA selected the Kuiper Belt object Ultima Thule as its next target. When New Horizons makes its closest approach on January 1, 2019, Ultima Thule will become the farthest object ever visited by a spacecraft.  

Home > Open > New Horizons Ultima Thule Encounter in 2019

 

Plus: what if our Sun was replaced with one of the largest known stars in the universe, the red supergiant Betelgeuse?

Home > Open > Solar System with Betelgeuse Instead of the Sun

This update also includes an improvement to the accuracy of positions for moons and other objects in the Solar System Now & Real Time simulation, plus a few other smaller improvements and bug fixes.

 

Check out a full list of What’s New in Update 21.3

Please report any issues on our forums (local forum | Steam forum) or in-game via Home > Send Feedback.


Universe Sandbox ² Featured in Vsauce Video

Friday, November 3rd: We’ve released Updates 20.2.3 and 20.2.4, which add two sims from this Vsauce video as well as a few improvements and bug fixes. See the sims in Home > Open.

Hey, did you hear that? Michael from Vsauce just gave some high praise of Universe Sandbox ²: “This simulator will blow your mind. I love it.”

Vsauce is a science and education YouTube channel that has attracted over 12.5 million subscribers with “videos that feed the curious and illuminate the amazing.”

We’re very honored and humbled to be featured in their latest video! Check it out below.
 

 

For the latest Universe Sandbox ² news, follow us on Twitter and Facebook.

See Asteroid 2012 TC4’s Trip Past Earth


 
On October 12, 2017, asteroid 2012 TC4 passed Earth early in the morning, flying above Antarctica at around 1:42am EDT.
 
See its close approach in Universe Sandbox ²:
Home > Open > Historical > 2012 TC4 Passes Earth on October 12, 2017
 
The roughly house-sized asteroid passed just a bit beyond the orbits of communications satellites, well within the Moon’s orbit. This wasn’t close enough to pose any threat, but its orbit was slightly changed by Earth’s gravity, as you can see in the GIF above from Universe Sandbox ². Learn more on NASA’s website
 
For the latest Universe Sandbox ² news, follow us on Twitter and Facebook.
 

Ciao, Cassini | Update 20.2

Run Steam to download Update 20.2, or buy Universe Sandbox ² via our website or the Steam Store.

November 3: Updates 20.2.3 and 20.2.4 are small updates which add two sims from the latest Vsauce video as well as a few improvements and bug fixes.

November 2: Update 20.2.2 is a minor update which includes a number of improvements and bug fixes.

October 5: Update 20.2.1 a minor update which adds a Cassini spacecraft model, Quicksave & Quickload (F5 & F9), and a number of smaller improvements and fixes.

 

On September 15, 2017, the world says goodbye to the Cassini spacecraft as it ends its historic mission with a final plunge into Saturn.

During its 13 years orbiting Saturn, Cassini made a number of invaluable discoveries about the planet, its rings, and its moons.

We now know that massive geysers covering the south polar region of the moon Enceladus shoot icy particles into space, forming most of Saturn’s E-ring and hinting at a massive, subsurface ocean. And we now know that the surface of Titan, Saturn’s biggest moon, shares a surprising number of characteristics with Earth, including dunes, mountain ranges, rivers, lakes, and seas.

With its array of sophisticated instruments, Cassini watched as storms raged on Saturn and seasons changed. It discovered eight new moons, provided insight into the behavior of its famous rings, and completely changed our understanding of its magnetosphere. The mission has been extended twice and now Cassini has been in orbit nine years longer than originally intended. Its fuel is nearly gone and so, to prevent possible contamination of any of the moons, its course has intentionally been set for disintegration in Saturn’s atmosphere.

So now we say ciao, Cassini. Thanks for all of your work.

And thanks to all of the hard-working scientists from NASA, the European Space Agency, and the Italian Space Agency who made the Cassini mission possible.

See Cassini’s final hours in Universe Sandbox ²

Home > Open > Core/Historical > Cassini collision with Saturn on September 15, 2017
Home > Tutorials > Science > What Is Cassini’s Grand Finale?

This update also includes a number of smaller improvements and bug fixes.

Check out the full list of What’s New.

 

For the latest Universe Sandbox ² news, follow us on Twitter and Facebook.

Science Works. Science Helps. Science Matters.


Observation. Hypothesis. Prediction. Experiment. Refine. Begin again.

Science is neither truth nor faith. Science is the process by which we reject or refine testable theories. These theories explain and predict the rules and processes that govern the behavior of the natural universe. Science doesn’t find universal objective truth; it narrows the error bars of our understanding. By its very definition, the scientific method works: if it is not reproducible, if it is not predictive, or if evidence rules it out, then it is rejected by science. And if it isn’t testable, then it isn’t in the realm of science (instead I would argue it is– and should remain– personal).

Science solves problems, and it solves them efficiently. Science makes us healthier, safer, more comfortable, and better at solving the problems of our daily lives. Applying the rigor of science to any decisions or areas of understanding that affect the lives of others can only serve to benefit lives and minds (for major decisions, not for when a friend wants you to choose the restaurant). Observation, hypothesis, prediction, experiment, analysis, adjust, rethink, repeat. We use the scientific method to make better meals, we can trust it to pick our diets, we can use the method to choose the best products, or to determine the best route to work.

Science and skepticism go hand in hand. We build our understanding of the world based on our observations of it, but also by the input of others. We can understand logical fallacies, accept new data, and test our assumptions against that data. In doing so, we can constantly refine and adapt our worldviews, and we can grow as people.

Science is not a political issue. The beauty of science is that it has to be reproducible and predictive. That means you don’t just have to believe what you are told. You can check for yourself! Some things might require expensive labs to verify, but if you, say, thought the world was flat, well you can check that!

Universe Sandbox ² is a live simulation that takes our understanding of the motion of objects and uses it to decide where each body will move as we step through simulation time. This matches closely to reality (at reasonable time steps, for non-relativistic situations) because science is reproductive and predictive. Society’s current understanding of physics allows us to send missions like Rosetta, or Juno, or New Horizons, billions of miles away to planned locations with an error equivalent to “throwing an object from New York and having it hit a particular key on a keyboard in San Francisco.”

Because this is how science works. Ignoring actionable, well-established scientific predictions is unconscionable. It’s plugging your ears and going “la la la” when someone tells you there’s an atrocity happening right behind your back, an atrocity that you have the power to stop. Not only can you turn your head and easily verify that the person is speaking the truth, but you can even do something to help, and instead you choose not to. Our choice cannot be to ignore this. Our choice matters. So today, I march for Science.

To very loosely quote Hank Green:
Science increases the Awesome and decreases the Suck in our world, and for that reason, I will always love it.

A note: I don’t want people confusing scientific institutions and cultures with the method itself. It is important to acknowledge the biases and failings of our scientific institutions historically and at present, especially with regard to equality and intersectionality, but let us not convolute science with academia or STEM institutions.