recursal/Fanatic-Fandom huggingface dataset:
Normalized Light Curve

The Normalized Light Curve property of an object represents the fraction of its light that can be seen by the camera. For a star with no other objects between the star and the camera, the Normalized Light Curve will be equal to one. Any object blocking part of the light from the star will decrease the Normalized Light Curve. If the object is not a star, the Normalized Light Curve will be zero. This is a **read-only** property that is automatically calculated by Universe Sandbox.

This property is called a "light curve" as a reference to the common exoplanet detection technique known as transit photometry. In this method, astronomers measure the amount of light coming from a star over time, constructing a plot of light vs. time, or a "light curve". An exoplanet orbiting at the right angle relative to the observer will pass between the star and the telescope, causing a dip in the light curve. In Universe Sandbox, the user can simulation this technique by using the Graph option for the Normalized Light Curve property.

## Property Details

### Location

The Normalized Light Curve property is located in the Camera Relative section of the Motion tab of an object's properties panel.
Sagathorn

**Sagathorn** is a magnus in Re:Legend.

## Description

The green on their bodies are actually moss and other vegetation attracted by the warmth

## Abilities

 Floral barrier

 Magical Defense +10%

## Reference

* Kickstarter Update #18 400% Funded, Playstation 4 stretch goal, Pick-a-Magnus Winner, Magnus Friday!

## Trivia

* Winner of the **Pick-a-Magnus Kickstarter Week 2** minigame during the Kickstarter campaign.
* Re:Legend - Magnus Lore Reveal #28  Sathorn - Steam News
* The ingame description says: "from the Rhidillon species".
Infrared Emissivity

The Infrared Emissivity of an object is a measure of how efficiently the top layer of the object's atmosphere will emit infrared radiation. An object with an emissivity of one is a perfect blackbody and will absorb incoming radiation and re-emit it as thermal infrared radiation based on its temperature. Objects with lower emissivity values will emit infrared radiation at lower rates. An object with a single-layer atmosphere with an emissivity of zero will be perfectly reflective, absorbing and re-emitting none of the incoming energy as heat.

## Property Details

### Location

The Infrared Emissivity property is located at the end of the Atmosphere section of the Surface tab of an object's properties panel. This section is only visible for Terrestrial Planets.

## Simulation Effects

### Surface Temperature

The emissivity of the atmosphere,

ϵ

{\displaystyle \epsilon}

, affects the amount of heat energy that the atmosphere will radiate in all directions, including back down towards the surface of the object. The rate at which energy is added to the object's surface from this atmosphere heating, or the Atmosphere Power, is estimated as

P

a
t
m

=
f
(
ϵ
)
σ

T
4

4
π

R
2

,

{\displaystyle P\_{atm} = f(\epsilon) \sigma T^4 4 \pi R^2,}

where

T

{\displaystyle T}

 is the Average Temperature of the object and

R

{\displaystyle R}

 is its Radius. The emissivity factor

f
(
ϵ
)

{\displaystyle f(\epsilon)}

 depends on the number of opaque layers that can represent the atmosphere,

N

{\displaystyle N}

:

f
(
ϵ
# )

(
2
N
−
2
)
−
(
N
−
2
)
ϵ

(
2
N
)
−
(
N
−
1
)
ϵ

.

{\displaystyle f(\epsilon) = \frac{(2 N - 2) - (N - 2) \epsilon}{(2N) - (N - 1)\epsilon}.}

If there is only one atmosphere layer, then

f
(
ϵ
# )

ϵ
2

.

{\displaystyle f(\epsilon) = \frac{\epsilon}{2}. }

This atmosphere power contributes to the total Energy Absorption Rate of the object, which is used to calculate its Average Temperature.

1. ↑ For example, see: American Chemical Society. A Single-Layer Atmosphere Model. *ACS Climate Science Toolkit: How Atmospheric Warming Works*.
2. ↑ For example, see: American Chemical Society. A Multilayer Atmosphere Model. *ACS Climate Science Toolkit: How Atmospheric Warming Works*.
Label

The Name of an object in a simulation can be displayed onscreen near the object with a Label.

## Related Settings

### Show Labels

Labels are on by default in most simulations. To toggle labels on and off, the user can use the L hotkey, the Labels toggle in the View menu in the bottom bar, or the Labels toggle in the full View Settings Menu.

### Label Properties

Additional settings in the View Settings menu control the opacity of labels, and whether the font size of the labels will be scaled to the mass of the objects.
Snow Appearance

The Snow Appearance control contains settings for the on-screen appearance of the object's simulated snow.

The checkbox on the left of the control determines whether the object's snow is displayed. The color setting on the right of the control sets the color of the snow.

## Property Details

### Location

The Snow Appearance control is located in the Layers section of the Visuals tab of an object's properties panel.
Human-Scale Object Appearance

The Tint property of a Human-Scale Object determines the source of the object's color. The property has two options: Default and Custom. When the Tint is set to Custom, the color of the object can be affected by the user.

## Property Details

### Location

The Tint property is located in the Layers section of the Visuals tab of the object's properties panel.
Gas Drag Power

The Gas Drag Power property of an object represents the rate that energy from supernova drag heating or other nearby explosions is added to the object over time. Supernova Drag Power is a **read-only** property that is continually calculated by Universe Sandbox.

## Property Details

### Location

For Planetary Body object, the Gas Drag Power property is located in the Energy Flow section of the object's Surface tab, when the Energy Absorption Rate property is expanded. For Stars, Black Holes, Fragments, and Human-Scale Objects, the Gas Drag Power property is located in the Temperature tab.

### Units

Gas Drag Power can be viewed using the following units:

* Solar luminosity (L star) = 3.846×1026 W
* Watts (W) is the SI unit for luminosity.

## Simulation Effects

### Temperature

Gas Drag Power is one of several sources of energy that can increase an object's Average Temperature or Surface Temperature.
Object Types

Within Universe Sandbox, objects are categorized based on their properties, particularly their mass. For performance reasons, not all simulation effects are calculated for each type of object. For example, Stellar Evolution is not simulated for planets.

The object types in Universe Sandbox include:

* Stars
* Planetary Bodies (including Planets, Exoplanets, Moons, and large Solar System Objects)
* Fragments (including small Solar System Objects)
* Human-Scale Objects
* Volatiles
* Black Holes
* Galaxies
* Galaxy Nebulae
* Supernova Clouds
* Barycenters
Distance

The Distance of an object is the difference between the object's position and some reference point, defined by the Relative to property. In terms of vector mathematics, the Distance is the magnitude of the object's Position Vector.

## Property Details

### Location

The Distance property for an object can be found near the top of the Motion tab. For Galaxy objects, the Distance property is located in the Properties section of the Galaxy tab, and refers specifically to the Black Hole's Distance. For Galaxy Nebula objects, the Distance property is located in the Motion section of the Nebula tab.

The Distance property can be expanded to show the object's Position Vector.

### Units

Distance can be viewed and edited using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Name

The Name of an object is a text label distinguishing the object from other objects in the simulation.

## Property Details

### Location

The Name of an object appears at the top of the property panel for that object, as well as anywhere that the object is referenced in other objects' properties (for example, as an Orbital Parent). The Name also appears onscreen as a label for the object.

The only place where the Name is editable is in the Overview tab, where it is the first property listed. For Galaxy objects, the editable Name property is located at the top of the Properties section in the Galaxy tab, and for Galaxy Nebula objects, the editable Name property is located at the top of the Nebula tab. For Supernova Cloud objects, the editable Name property is located at the top of the Properties section in the Nova tab.
Force Tool

The Force Tool applies a force that, when aimed at an object, will either spin or push the object:

**Spin** applies a rotational force at the location of the cursor while the object is held in place. The farther from the center of the object, the more acceleration this force will apply. This can also change the object's Rotation Axis.

**Push** applies a gravitational force to objects within a cone-shaped region extending outwards from the camera location. This force is attractive but can be made repulsive by using a negative Equivalent Mass.

## Tool Details

### Location

The Force button is located in the Tools menu in the bottom bar. When clicked, a menu with several settings will appear.

### Settings

The Force Tool has a number of settings that affect the strength of the force and the region of space that is affected.

* Spin/Push: The toggle at the top of the menu can be used to switch between Spin and Push.
* Auto Force: When on, the Force value will be set automatically based on the object's mass.
* Force: The magnitude of the force applied to the object.
* (Spin) Acceleration: The rate at which the object's rotation or motion is accelerated by the tool's force
* Target Object: Shows selected properties of the target object of the tool
	+ Name: The target object's name
	+ Spin Rate: How fast the object is rotating
	+ Distance to Camera: The distance between the camera and the target object
	+ Show Arrow: Displays an arrow from the center of the object to the cursor when the cursor is hovering over the object
	+ Show Axis: Displays the object's Rotation Axis onscreen when the cursor is hovering over the object
Human-Scale Object

A Human-Scale Object in Universe Sandbox is a simulated object representing an actual or fictional artificial object in the size range of the everyday human experience, from objects small enough to be held (such as a bowling ball), to objects larger than buildings (such as the Great Pyramid of Giza).

## Properties Panel

The properties panel for a Human-Scale object will include the following tabs:

* Overview
* Motion
* Composition
* Temperature
* Actions

## Characteristics

Human-Scale Objects have the following characteristics:

* They are attracting objects, meaning that they exert a gravitational force on other objects in the simulation.
* They are attracted objects, meaning that they feel the effects of gravity from other attracting objects in the simulation.
* They have calculated orbital elements, and their orbit can be displayed.
* They can collide with other objects.
* They have a surface temperature, distinct from their internal effective temperature.
* They have a simulated composition.
Temperature Stable Simulation Speed

As with most simulated physics in Universe Sandbox, the accuracy of the simulated diffusion of heat across the surface of an object is limited by the Simulation Speed of the simulation. In the case of the 2D temperature simulation, high simulation speeds can also create instabilities in the simulation, leading to strange-looking behavior in the Temperature map. The simulation speed above which the temperature simulation becomes significantly inaccurate and potentially unstable is usually much lower than the maximum allowed simulation speed for N-Body Simulation. This property is **read-only** and is automatically calculated by Universe Sandbox.

## Property Details

### Location

The Temperature Stable Simulation Speed property can be found in the Advanced Simulation section at the bottom of the Surface tab in the object's properties panel.

### Units

Temperature Stable Simulation Speed can viewed using the following units:

* Gigayears per real-time second (G years/sec) = 109 years/sec
* Megayears per real-time second (M years/sec) = 106 years/sec
* Years per real-time second (years/sec) = 365.25 days/sec
* Months per real-time second (months/sec) = 1/12 years/sec
* Days per real-time second (days/sec) = 24 hours/sec
* Hours per real-time second (hours/sec) = 60 mins/sec
* Minutes per real-time second (mins/sec) = 60 sec/sec
* Seconds per real-time second (sec/sec) means the simulation is running in real time
* Milliseconds per real-time second (ms/sec) = 0.001 sec/sec
Boiling Point

The Boiling Point of an object represents the temperature at which water will change from the liquid to gas state. Above this temperature, the water will exist as a gas, and below this temperature, it will exist as a liquid or solid.

This property is read-only and is automatically calculated by Universe Sandbox based on the Surface Pressure of the object.

## Property Details

### Location

The Boiling Point property is located in the Water section of the Surface tab of the object's properties panel.

### Units

Boiling Point can be viewed using the following units:

* Kelvin (K) is the SI base unit for temperature
* Degrees Fahrenheit (°F)
* Degrees Celsius (°C)

Conversions between these three units are as follows:

°C = K - 273

°F = (9/5)°C + 32
Surface Pressure

The Surface Pressure of an object is the force per unit area that the object's atmosphere exerts on its surface.

## Property Details

### Location

The Surface Pressure property is located in the Atmosphere section of the Surface tab of the object's properties panel. This section is only visible for Terrestrial Planets.

### Units

Surface Pressure can be viewed and edited using the following units:

* Standard atmosphere (atm) = 101325 Pa
* Bar (bar) = 100000 Pa
* Kilopascal (kPa) = 1000 Pa
* Millibar (mbar) = 100 Pa
* Pascal (Pa) is the SI unit for pressure.

## Simulation Effects

### Atmosphere Mass

The Surface Pressure is related to the atmosphere mass, *Matmo*, and radius of the object, *R*, and the surface gravity, *gs*, of the object by the following equation:

# P

g

s

M

a
t
m
o

4
π

R
2

{\displaystyle P = \frac{g\_{s} M\_{atmo}}{4\pi R^2}}

Surface Pressure will determine the Boiling Point and Freezing Point of water on the surface of an object.
Total Water Vapor Mass

Total Water Vapor Mass indicates the total mass of water present on the object's surface in the gas phase. This property is **read-only** and is automatically calculated by Universe Sandbox.

## Property Details

### Location

The Total Water Vapor Mass property of an object is located in the Water section of the Surface tab in the object's properties panel. For Terrestrial Planets, it can also be found by expanding the Atmosphere Mass property in the Atmosphere section of the Surface tab.

### Units

Total Water Vapor Mass can be viewed and edited using the following units:

* Milky Way Galaxy mass (milky way) = 1.5×1012 sun
* Solar mass (sun) = 1.9891×1030 kg
* Jupiter mass (jupiter) = 1.8986×1027 kg
* Earth mass (earth) = 5.97219×1024 kg
* Moon mass (moon) = 7.349×1022 kg
* Earth ocean mass (ocean) = 1.4×1021 kg
* Earth atmosphere mass (atmosphere) = 5.158×1018 kg
* Kilogram (kg) is the SI base unit for mass
* Gram (g) = 1×10-3 kg
* Milligram (mg) = 1×10-6 kg
Tidal Stress Magnitude

The Tidal Stress Magnitude property represents the total strength of the tidal forces acting on the object. This is a **read-only** property that is automatically calculated by Universe Sandbox.

## Property Details

### Location

The Tidal Stress Magnitude property is located in the Tidal Effects section in the Motion tab of the object's properties panel.

### Units

Tidal Stress Magnitude can be viewed using the following units:

* Dyne (dyn) = 10-5 N
* Newton (N) is the SI unit for force.
* Kilopascal (kp) = 0.10197 N
Locked Properties

Some properties in Universe Sandbox are locked to other properties. A set of (usually three) locked properties depend on each other, such that setting any two of the properties will automatically set the third. The user can determine which property to keep constant by "locking" the icon next to that property.

Locked properties can be identified by the locked icons that appear next to their text boxes in a property or settings panel.

## Examples

* Mass, Radius, and Density for most objects
* Mass, Radius, Density, and Age for Stars
* Radius, Total Power, and Power per Area settings for the Laser tool
Gravity

In Universe Sandbox, two objects in a simulation will exert an attracting force on each other due to gravity. This force will affect their motion over time.

## Physics

The strength of the gravitational force depends on the mass of each object, *M*1 and *M*2, the distance between the objects, *d*, and the gravitational constant of the simulation, *G*, according to the following equation:

# F
G

M

1

M

2

d

2

.

{\displaystyle F=G{\frac {M\_{1}M\_{2}}{d^{2}}}.}

This force will affect each object's velocity. The acceleration, or change in velocity over time, of each object depends only on the other object's mass, not its own. For example, the acceleration of object 1 due to gravity would be

a

1

=
G

M

2

d

2

.

{\displaystyle a\_{1}=G{\frac {M\_{2}}{d^{2}}}.}

The effects of gravity on the motion of objects in a simulation is simulated by Universe Sandbox's N-body simulation, which calculates the forces acting on each object at every time step, the accelerations that these forces would cause, and the movement of the objects as a result.

## Special Cases

For performance reasons, not all objects in Universe Sandbox simulate the effects of gravity. Objects that are non-attracting, such as fragments, will not exert a gravitational force on other objects. Object that are non-attracted, such as supernova clouds, will not feel the gravitational force of other objects.
Oblateness

The Oblateness of an object represents how much its shape differs from a perfect sphere.

## Property Details

### Location

The Oblateness property of an object can be found in the Overview tab in the properties panel, but only when the experimental Enable Non-Spherical Gravity toggle is turned on in the Debug tab of the Game Settings Menu.

### Units

A larger Oblateness value indicates a flatter and less spherical object, and will produce a larger effect in Universe Sandbox's non-spherical gravity model, which simulates the different strength and direction of the gravitational force produced by a non-spherical object.
Maximum Cloud Radius

The Maximum Cloud Radius property of a supernova represents the maximum distance between a Supernova Cloud object and the Origin of the supernova. This is a **read-only** property that Universe Sandbox calculates automatically as the supernova expands.

## Property Details

### Location

The Maximum Cloud Radius of a supernova is located near the top of the Properties section of the Nova tab in the properties panel of any of the Supernova Clouds making up that nebula.

### Units

Maximum Cloud Radius can be viewed using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Stabilize Temperature

The Stabilize Temperature action instantly sets the temperature of each point on the object's surface to that point's Effective Temperature, as calculated based on the incoming and outgoing energy.

If the object is rotating relative to the star it is orbiting, the incoming Stellar Power will be averaged over the object's surface based on its Rotation Axis. If the object's Rotational Period is equal to its Orbital Period, however, indicating that the object is tidally locked, the Stellar Power will not be averaged across the surface.

## Property Details

### Location

The Stabilize Temperature button can be found at the bottom of the Temperature section of the Surface tab in the object's properties panel.
Galaxy Radius

The Radius of a Galaxy objects is the distance between the Black Hole at the center of the galaxy and the outermost Galaxy Nebula object. The Radius property of galaxies in Universe Sandbox is not automatically calculated, and will not adjust if the galaxy changes shape during a collision with another galaxy. However, if the user adjusts the Radius, the Position Vector and Radius of each Galaxy Nebula in the galaxy will adjust to correct the size of the galaxy.

## Property Details

### Location

The Radius property of a galaxy can be found near the top of the Galaxy tab. The Radius of a galaxy is also displayed in its mini-info panel.

### Units

Radius can be viewed and edited using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Surface Gravity

The Surface Gravity of an object is the acceleration due to gravity felt on the surface of the object. The Surface Gravity of an object with a mass of *M* and a radius of *R* in a simulation with a gravitational constant of *G* is

g
s

=

G
M

R
2

.

{\displaystyle g\_s = \frac{GM}{R^2}.}

Surface Gravity is a **read-only** property and is automatically calculated by Universe Sandbox.

## Property Details

### Location

The Surface Gravity property of an object can be found in the Overview tab in the properties panel, and in the Cumulative Properties section of the Composition tab.

### Units

Surface Gravity can be viewed using the following units:

* Earth surface gravity (earth) = 9.80665 m/s2
* Meters per seconds squared (m/s2) is the SI unit for acceleration.
Elliptical Galaxy

An Elliptical Galaxy is a type of Galaxy object representing a specific elliptical-type galaxy, or a new elliptical galaxy created by the user. Elliptical galaxies are characterized by their ellipsoidal shape, relatively featureless structure, lack of dust, and reddish color indicating the presence of older, cooler, less massive stars.

## Related Properties and Settings

### Properties

* The Galaxy Type is located in the Galaxy tab of the Galaxy's properties panel. When the type is set to one of the elliptical types, the following property will appear:
* The Elliptical Ratio represents the ratio of the length of the shortest axis of the galaxy to the length of its longest axis. A spherical galaxy will have an Elliptical Ratio of 1.
* The appearance of an individual Galaxy Nebula object is controlled by the Gas Fraction, Star Fraction, Dust Fraction, and Average Star Temperature properties in the Nebula tab of the nebula's properties panel.

## Models

The structure of an elliptical galaxy in simulated to create a galaxy with a spheroidal shape (i.e., an ellipsoid with two equal axes and a third, potentially smaller axis). The ratio of the smaller axis to the longest is set by the Elliptical Ratio of the galaxy. The orbits of the Galaxy Nebula objects in the galaxy are carefully calculated to constrain the nebulae within this spheroid shape.

There is minimal simulated evolution of the Galaxy Nebula objects in an elliptical galaxy. The Average Star Temperature of the nebulae in an elliptical galaxy is set to a low temperature, to simulate the cooler, older stars commonly seen in these galaxies. The Dust Fraction for all nebula is set to 0%.

Elliptical galaxies are simulated with the following subtypes, which determine the Elliptical Ratio, *E*:

* E0: *E* = 1
* E1: 0.95 ≤ *E* < 1
* E2: 0.9 ≤ *E* <0.95
* E3: 0.85 ≤ *E* <0.9
* E4: 0.8 ≤ *E* <0.85
* E5: 0.85 ≤ *E* <0.8
* E6: 0.8 ≤ *E* <0.75
* E7: 0.75 ≤ *E* <0.7

Type E0 galaxies are spherical, while type E7 galaxies are the most "squashed" in appearance.
Supernova Origin

The Origin property of a Supernova Cloud object indicates the 3D location where the supernova occurred relative to the Simulation Grid, and thus where the cloud originated. This is a **read-only** property that is automatically calculated by Universe Sandbox. Like the Position Vector property of an object, the Origin is a 3D vector, with x-, y-, and z-components.

## Property Details

### Location

The Origin property is located in the Properties section of the Nova tab in the Supernova Cloud's properties panel.

### Units

Each component of the Origin can be viewed using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Supernova Power

The Supernova Power property of an object represents the rate that energy from supernova heating is absorbed by the object over time. Supernova Power is a **read-only** property that is continually calculated by Universe Sandbox.

## Property Details

### Location

For Planetary Body object, the Supernova Power property is located in the Energy Flow section of the object's Surface tab, when the Energy Absorption Rate property is expanded. For Stars, Black Holes, Fragments, and Human-Scale Objects, the Stellar Power property is located in the Temperature tab.

### Units

Supernova Power can be viewed using the following units:

* Solar luminosity (L star) = 3.846×1026 W
* Watts (W) is the SI unit for luminosity.

## Simulation Effects

### Temperature

Supernova Power is one of several sources of energy that can increase an object's Average Temperature or Surface Temperature.
Non-Spherical Gravity

Universe Sandbox can simulate non-spherical gravity as an experimental mode, activated using the Enable Non-Spherical Gravity in the Debug section of the Game Settings Menu.

Normally, N-body simulations like Universe Sandbox assume that each object in the simulation is a perfect sphere, attracting other objects directly towards the center of this sphere with the same force, regardless of the direction. However, in reality, most stars, planets, and moons are not perfectly spherical, but slightly squashed, and have some non-zero Oblateness representing the amount to which they deviate from a perfect sphere.

This non-spherical distribution of mass means that the gravitational force attracting nearby objects can have a different strength and even direction depending on where the attracted object is relative to the shape of the attracting object. For example, an object directly above the pole of a non-spherical attractor would feel a slightly weaker gravitational attraction than an object directly above its equator. And an object above a latitude between the pole and equator would feel a gravitational pull not towards the center of the non-spherical attractor, but also slightly towards its equator.

This variation in the force of gravity can alter the orbit of the attracted body, causing its orbit to shift or precess over time.
Momentum Conservation

One of the fundamental laws of the universe that any classical physics simulator, including Universe Sandbox, must follow in order to be able to reproduce realistic motions is the conservation of momentum. Momentum cannot be created nor destroyed, only transferred between objects, so the total momentum of a simulation must remain constant. This is especially important for collisions, in which momentum is exchanged between the colliding objects as they alter each other's velocities.

A similar fundamental law is the conservation of angular momentum: the total angular momentum of a simulation must also remain constant.

## Related Properties & Settings

### Properties

* The amount of momentum that is lost in the simulation due to the loss of mass (see Limitations) can be seen in the Stats menu in the bottom bar.

## Models

Consider an object with mass *M*1 and velocity *V*1 colliding with another object with mass *M*2 and velocity *V*2. Before the collision, the total momentum of this simulation is

P

i
n
i
t
i
a
l

=

M

1

V

1

M

2

V

2

.

{\displaystyle P\_{initial}=M\_{1}V\_{1}+M\_{2}V\_{2}.}

After the collision, the two objects may have new velocities and even new masses, if some of the mass transferred from one body to the other during the collision. Suppose that after the collision, object 1 has mass *m*1 and velocity *v*1, and object 2 has mass *m*2 and velocity *v*2. Then the total momentum of the simulation after the collision is

P

f
i
n
a
l

=

m

1

v

1

m

2

v

2

.

{\displaystyle P\_{final}=m\_{1}v\_{1}+m\_{2}v\_{2}.}

According to the law of conservation of momentum, momentum cannot be created or destroyed, so the total momentum of the simulation must be the same before and after the collision:

M

1

V

1

M

2

V

2

=

m

1

v

1

m

2

v

2

.

{\displaystyle M\_{1}V\_{1}+M\_{2}V\_{2}=m\_{1}v\_{1}+m\_{2}v\_{2}.}

Universe Sandbox uses this equation to help calculate what the new velocities, *v*1 and *v*2, of the objects will be after the collision.

## Limitations

Occasionally, mass is lost from the simulation for performance reasons. This lost mass carries with it some momentum, which is therefore also lost from the simulation.
Distance to You

The Distance to You property of an object represents the simulated distance between the object and the virtual camera through which the user views the simulation. Distance to You is a **read-only** property, and will change as the user moves the camera through the simulation, or as the object moves relative to the camera position.

## Property Details

### Location

The Distance to You property can be found in the Overview tab, and at the end of the Camera Relative section of the Motion tab. For Galaxy Nebula objects, the Distance to You property is located at the end of the Motion section of the Nebula tab. For Galaxy objects, the Distance to You property is located near the end of the Properties section of the Galaxy tab, and refers specifically to the Distance to You property of the Black Hole.

### Units

Distance to You can be viewed using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Attracted

Attracted objects feel the gravitational force of attracting objects in the simulation, and their motion will be affected. Most object types in Universe Sandbox are attracted, but some are not for performance reasons.

Attracted object types include:

* Stars
* Planetary Bodies
* Fragments
* Human-Scale Objects
* Black Holes
* Galaxy Nebulae

Non-attracted object types include:

* Volatiles
* Supernova Clouds
Tidal Heating per Mass

The Tidal Heating per Mass property of an object represents the amount of energy over time the object absorbs per unit mass due to tidal heating. This property is **read-only** and automatically calculated by dividing the object's Tidal Heating Effect by its Mass.

## Property Details

### Units

Tidal Heating per Mass can be viewed using the following units:

* Megawatts per kilogram (MW/kg) = 106 W/kg
* Watts per kilogram (W/kg) uses the SI units for power and mass.
Stabilize Phases

The Stabilize Phases action instantly converts the water in each point on the object's surface to the solid, liquid, or gas phase based on the point's Sea Level Temperature.

## Property Details

### Location

The Stabilize Phases button can be found along the top of the Water section of the Surface tab in the object's properties panel.
Selected Cell Ice Depth

The Ice Depth property indicates the depth of the ice in the selected cell.

## Property Details

### Location

The Ice Depth property is located in the Selected Grid Cell section of the Surface tab in the object's properties panel.

### Units

Ice Depth can be viewed and edited using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Roche Fragmentation

If an object comes within a certain distance of its Orbital Parent, tidal forces from the parent object will be strong enough to tear apart the orbiting object, creating fragments. This critical distance, known as the Roche limit, depends on the radius of the parent object and the densities of both objects.

## Related Properties & Settings

### Settings

* The production of all fragments can be turned off using the Fragment toggle in the Sim menu in the bottom bar, or using the Create Fragments toggle in the full Sim Settings Menu. Roche fragmentation (as opposed to collision fragmentation or friction fragmentation can be individually controlled in the Sim Settings Menu.

## Models

Roche fragmentation occurs when the force of gravity from other objects in the simulation is stronger than the internal forces holding an object together (including its own gravity). Due to performance constraints, Universe Sandbox generally simulates an object as a single body rather than a collection of bodies held together by gravity. To model the interplay between these competing forces, each object with a radius larger than 100 km contains 100 "sample fragments". These non-attracting objects are not visible to the user and do not collide with each other or with other objects, but their motion is simulated by the *N*-body integrator as they feel the effects of gravity from other objects in the simulation, including their own parent object.

The sample fragments are created inside their parent object, randomly oriented at a distance of 0.8*R* from the object's center, where *R* is the radius of the parent object. They are given the same velocity as the parent object, but are then allowed to move under the influence of gravity. If a fragment is pulled too close to the center of the object, it is placed back at the 0.8*R* distance. If a fragment is pulled too far from the center, to a distance of 0.9*R*, this indicates that the forces of gravity from other objects is large enough to cause Roche fragmentation. The sample fragment is replaced with a true Fragment object, which will be visible to the user as it is pulled out of the parent object's surface. This object is given the position and velocity of the sample fragment it replaced.

The mass of each new Fragment object is calculated by estimating the rate at which mass would be lost to Roche fragmentation, such that each fragment can carry away no more that 1/100 of the mass of the parent object. This mass is then subtracted from the mass of the parent object. The density of each fragment is randomly chosen from the range of 0.1ρ-ρ, where ρ is the density of the parent object, and the radius of the fragment is calculated from its mass and density. The fragment is given a randomly oriented rotation axis and a rotation period equal to the parent object's.
Babioles

Les **babioles** sont des objets spéciaux qui occupent leur propre emplacement dans l'inventaire et apportent des bonus passifs. Sans certains objets spécifiques, Isaac ne peut porter qu'une babiole, et celle-ci peut être lâchée.

Le DLC 'The Wrath of the Lamb' du jeu *The Binding of Isaac* original a introduit les babioles en tant que mécanique de jeu et comptait 33 babioles.

Rebirth ajoute 27 babioles, pour un total de 60.

Afterbirth ajoute 29 babioles pour un total de 89.

Afterbirth † ajoute 38 babioles, pour un total de 127.

Repentance ajoute 61 babioles, pour un total de 188.

## Notes

* Le  et  permettent à Isaac de porter deux babioles à la fois.
* Avaler une babiole libère l'emplacement et active ses effets de manière permanente.
	+ La , le  et la  pilule Gloups ! permettent d'avaler une babiole.
* Maintenir la touche ou le bouton assigné à "Lâcher" dans les paramètres des contrôles permet de retirer les babioles portées de leur emplacement et de les poser au sol.
	+ Il est impossible de lâcher la .
* Une fois la mécanique débloquée, les babioles sont parfois dorées.
	+ L'effet des babioles dorées est doublé si possible.
* La  double l'effet de la plupart des babioles tant qu'elle est portée.
	+ Porter la Boîte de Maman et une babiole dorée triple l'effet de la babiole.
* Les babioles apparaissent dans un ordre défini par la graine de la partie et, hors exceptions, les babioles ne peuvent apparaître qu'une fois pendant une partie.
	+ Le  est garanti d'apparaître à l'obtention de l' et la  est garantie d'apparaître après avoir battu  Ultra Orgueil. Celles-ci peuvent apparaître plusieurs fois si ces actions sont effectuées à nouveau.
	+ Le  apparaît parfois en cassant un vase et le  en détruisant un polype, mais celles-ci ne peuvent pas rapparaître.
	+ Si toutes les babioles ont été rencontrées dans une partie, le cycle recommence et les babioles peuvent apparaître à nouveau.
* Deux babioles identiques peuvent être portées si Isaac avale l'une avec une  pilule Gloups ! et porte l'autre, mais leurs effets ne peuvent que rarement être cumulés.
	+ Les effets de plusieurs babioles identiques peuvent être cumulés, et deux babioles identiques peuvent être portées avec  ou . Les effets d'un grand nombre de babioles ne peuvent pas être cumulés, surtout ceux qui sont plus complexes qu'une simple augmentation de statistiques.
* , le  et la  Rune Jera ne peuvent pas dupliquer une babiole.

## Anecdotes

* était une babiole dans le jeu *The Binding of Isaac* original.
	+ Le  était un objet dans le jeu *The Binding of Isaac* original.
* Le nombre total de babioles à la sortie d'Afterbirth+ était de 29. 9 babioles supplémentaires ont été ajoutées dans les Booster Packs.

* Le Game Squid est la seule babiole du jeu *The Binding of Isaac* original à ne pas avoir été ajoutée à Rebirth ou ses DLC; probablement parce qu'il a été introduit dans l'Eternal Edition, après la sortie de Rebirth.
	+ Le  a un effet presque identique à celui du Game Squid.
Camera

The user views the simulation through a virtual camera. This camera can be controlled by the user to move around the simulation, zoom in and out, and change the angle at which the simulation is viewed.

## Controls

### Keyboard

A user with a keyboard can perform the following actions:

* up/down arrow keys: zoom in and out on the camera-locked object

* left/right arrow keys: rotate around the camera-locked object, or around the camera itself if the object is not locked on an object

* A/D keys: move the camera left or right

* R/F keys: move the camera up or down

* W/S keys: move the camera forward or backwards

* C key: land the camera on the surface of the selected object

### Mouse

A user with a mouse can perform the following actions:

* Double-click on object: locks the camera onto the object, so that the object is always at the center of the screen unless the user shifts the camera away

* Hold and drag: rotates the camera around the camera-locked object, or around the camera itself if the camera is not locked on an object

The game has no invert y-axis option yet -\_-

## Properties

Properties related to the camera can be viewed for a specific object in the Camera Relative section of the Motion tab of the object's properties panel. These include Camera Inclination and Camera Azimuth.
Position Vector

The Position Vector describes an object's 3D location in the simulation. This vector has three components, representing the object's distance in the x, y, and z directions from the reference object indicated by the Relative to property.

## Property Details

### Location

The Position Vector property can be found by expanding the Distance property near the top of the Motion tab of the object's properties panel. For Galaxy objects, the Distance property is located in the Properties section of the Galaxy tab, and the Position Vector refers specifically to the Black Hole's Position Vector. For Galaxy Nebula objects, the Distance property is located in the Motion section of the Nebula tab.

### Units

Each component of the Position Vector can be viewed and edited using the following units:

* Milky Way Galaxy radius (milky way) = 5.5×104 light year
* Parsec (parsec) = 3.08568025×1016 m
* Light-year (light year) = 9.46073047×1015 m
* Astronomical Unit (AU) = 1.495978707×1011 m
* Solar radius (sun) = 6.955×108 m
* Lunar distance (lunar dist) = 3.844×108 m
* Light-second (light sec) = 2.99792458×108 m
* Jupiter radius (jupiter) = 6.9911×107 m
* Earth radius (earth) = 6.37101×106 m
* Moon radius (moon) = 1.7371×106 m
* Kilometer (km) = 1000 m
* Meter (m) is the SI base unit for length
* Centimeter (cm) = 0.01 m
* Millimeter (mm) = 0.001 m
Simulated Nebulae Count

The Simulated Nebulae Count property of a galaxy indicates the number of galaxy nebula objects that make up the galaxy. If the user changes the Simulated Nebulae Count, the Radius of each galaxy nebula object will automatically adjust to keep the ratio of nebula size to galaxy size constant.

## Property Details

### Location

The Simulated Nebula Count property is located near the end of the Properties section of the Galaxy tab in the galaxy's properties panel.

## Simulation Effects

### Performance

A galaxy with a higher Simulated Nebulae Count will have more visible detail and structure, due to the higher resolution. However, increasing the number of nebulae in a galaxy will add objects to the simulation, decreasing the performance.
Solar System Object

A Solar System Object in Universe Sandbox is a simulated object representing an actual asteroid, comet, Kuiper Belt object, dwarf planet, or other natural body orbiting the Sun that is not a planet or moon.

Larger Solar System objects, such as dwarf planets, are simulated as Planetary Bodies in Universe Sandbox, while smaller objects, such as small asteroids and Kuiper Belt objects in the Solar System simulations, are simulated as Fragments for performance reasons.

## Database

There are over 50,000 Solar System objects in the Universe Sandbox database, which are sourced from the NASA Jet Propulsion Laboratory's Small-Body Database.
Selected Cell Sea Level Temperature

The Sea Level Temperature property indicates the Sea Level Temperature of the selected cell.

## Property Details

### Location

The Sea Level Temperature property is located in the Selected Grid Cell section of the Surface tab in the object's properties panel.

### Units

Sea Level Temperature can be viewed and edited using the following units:

* Kelvin (K) is the SI base unit for temperature
* Degrees Fahrenheit (°F)
* Degrees Celsius (°C)

Conversions between these three units are as follows:

°C = K - 273

°F = (9/5)°C + 32
Target Simulation Speed

The Target Simulation Speed is the Simulation Speed at which Universe Sandbox is attempting to run the simulation. The Target Simulation Speed is set by the user or by a prebuilt simulation, but the actual Simulation Speed at any given point may vary from the Target Simulation Speed due to performance constraints.

## Setting Details

### Location

The Target Simulation Speed setting is located in the Time menu in the bottom bar, as well as in the Time section of the Sim Settings Menu.

### Units

Target Simulation Speed can viewed and edited using the following units:

* Gigayears per real-time second (G years/sec) = 109 years/sec
* Megayears per real-time second (M years/sec) = 106 years/sec
* Years per real-time second (years/sec) = 365.25 days/sec
* Months per real-time second (months/sec) = 1/12 years/sec
* Days per real-time second (days/sec) = 24 hours/sec
* Hours per real-time second (hours/sec) = 60 mins/sec
* Minutes per real-time second (mins/sec) = 60 sec/sec
* Seconds per real-time second (sec/sec) means the simulation is running in real time
* Milliseconds per real-time second (ms/sec) = 0.001 sec/sec
Barycenter Mass

The Total Mass property of a Barycenter object represents the sum of the masses of the objects orbiting the barycenter. This property is **read-only** and is automatically calculated by Universe Sandbox.

## Property Details

### Location

The Total Mass property is located near the top of the Barycenter tab of the barycenter's properties panel.

### Units

Total Mass can be viewed and edited using the following units:

* Milky Way Galaxy mass (milky way) = 1.5×1012 sun
* Solar mass (sun) = 1.9891×1030 kg
* Jupiter mass (jupiter) = 1.8986×1027 kg
* Earth mass (earth) = 5.97219×1024 kg
* Moon mass (moon) = 7.349×1022 kg
* Earth ocean mass (ocean) = 1.4×1021 kg
* Earth atmosphere mass (atmosphere) = 5.158×1018 kg
* Kilogram (kg) is the SI base unit for mass
* Gram (g) = 1×10-3 kg
* Milligram (mg) = 1×10-6 kg
Add Moons to Planet

The Add Moons to Planet action will add any known moons for the selected planet in the Universe Sandbox database to the simulation. The moons will be given their known orbits around the planet. If the Add Moons to Planet button is pressed multiple times, multiple copies of each moon will be added to the simulation.

## Property Details

### Location

The Add Moons to Planet action is located in the Misc section of the Actions tab of a planet's properties panel, if the planet has moons listed in the Universe Sandbox database.
Rotation Lock

The Rotation Lock property determines whether the object will appear to rotate onscreen. When on, the object will appear to have no rotation, allowing the user to view one side of the object continuously even at high Simulation Speeds. However, the object will continue to experience the simulated effects of rotation, such as the spreading and retreating of ice across the surface of the Earth as the seasons pass.

## Property Details

### Location

The Rotation Lock property is located in the Display Settings section of the Actions tab of the object's properties panel.