Sky and Viewing Options


Sky and Viewing Options Window   [F4]

The options in this window allows you to set how the sky is rendered, what grids and lines are shown, the landscape image to be used and the selection of star lore that specifies the star names and constellations to be displayed.


Sky Options 

This tab controls the display of the stars, planets and satellites, atmosphere, labels, and shooting stars.

Stars Display Options



Absolute Scale

Absolute scale lets you increase or decrease the brightness of all stars by the same amount. Bright stars will have brighter and larger disks, while dim stars will become more apparent.

Relative Scale

Relative scale lets you increase or decrease the brightness of stars relative to their magnitudes. For example, if star1 is twice as bright as star 2, changing the values up or down will have an effect on star1 double that of star2.

Twinkle

This option controls how much the stars twinkle.

Dynamic Eye Adaptation

When enabled this feature reduces the brightness of faint objects when a bright object is in the field of view. This simulates how the eye can be dazzled by a bright object such as the moon, making it harder to see faint stars and galaxies.

Atmosphere Options


Show Atmosphere

This option, when enabled, will simulate the light and darkness during the day and night. If it is disabled, atmospheric effect on seeing is canceled, the sky will be dark and stars with other sky objects will be displayed even during day time. 

Atmosphere disabled                                                                        Atmosphere enabled

Light Pollution

This options simulates the level of light pollution.  Light pollution is the effect of artificial light on seeing the sky objects. The scale used is Bortle Dark-Sky Scale, with1 meaning an excellent dark sky site and 9 a badly light polluted site. It is useful to know what stars is expected to be seen in a particular site. 

Refraction/Extinction Settings


This option will simulate atmospheric refraction and extinction effects on sky objects. The refraction effect of the atmosphere makes the sun, the moon and stars visible over the horizon before they actually rise or after they actually set. The refraction option will be enabled if the "Show Atmosphere" option is enabled. The rise and set times of sun and moon using this option will be closer to the apparent rise and set time in reality.

The apparent sun position caused by refraction as opposed to real position.

Atmospheric refraction is affected by the increase or decrease of pressure and temperature. If you want to closely simulate your current conditions, enter these values in the corresponding fields.

If you want to cancel the refraction effect, set the pressure to 0.

Extinction Coefficient refers to the loss of starlight in passing through Earth atmosphere. If a star is near the horizon its light path through the atmosphere is longer and it will be dimmed more. For excellent mountain top conditions use a value of 0.12, For a good rural site use a value of 0.2 and for murky conditions use 0.35.

If you want to cancel the extinction effect, set the extinction coefficient to 0.

Planets and Satellites


Show planets: Display or hide the solar system objects including the sun and the moon.

Show planet markers: Displays a marking circle around the planet.

Show planet orbits: Displays the orbit path of the planets.

Simulate light speed: Normally, Stellarium shows you the positions of the planets as they are now in space. If you turn this feature on, the delay caused by light propagation will change the apparent positions of the planets. For a good example, toggle this option while zoomed into Jupiter.

Scale Moon: This will increase the size of the Moon for better visibility and to enable clearer Stellarium screen shots of the sky when the Moon is a main object.

A shot showing planet marker around Venus and its orbit.

Labels and Markers


Stars: When checked will show stars labels. To show only labels of bright stars keep the button closer to the left and to show labels of dim stars move the button to the right.

Nebulas: When Checked, nebulas will be shown while sliding the button to the right will show dim nebulas and their labels. Nebulas will be hidden if the box is unchecked.

Planets: Planets labels will be shown if this box is checked. The slider button function is unclear for me.

Note that when you zoom in you will see more labels.

Shooting Stars


Select a value of meteors per hour to simulate a meteor shower with the rate selected.
0: No shooting stars
10: Normal rate
80: Standard Perseids rate
10000: Exceptional Leonids rate
144000: Highest rate ever (1996 Leonids)
Note that this is just a simulation and not a prediction of the density of periodical meteor showers.
A shot of meteor shower simulation

Markings 

Understanding the sky display is enhanced by various plots of grids, constellation lines, figures and labels.You can also select one among various projection methods to display the sky.



Celestial Sphere

Options are provided to plot different celestial coordinate systems and show lines of special significance. 


Equatorial Grid

Equatorial grid will display the lines of the Equatorial coordinate system. The Equatorial coordinate systems functions by projecting the Earth's geographic poles and equator onto the celestial sphere. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, the projections of the Earth's north and south geographic poles become the north and south celestial poles, respectively. The lines parallel to the celestial equator describe the declination (Dec), the angle above or below celestial equator while the lines running from north to south describe the right ascension (RA), the angle east of the point of March equinox. This coordinate system is fixed to the sky, meaning a star will have a fixed equatorial coordinates regardless of the time of day or night.


Equatorial J2000 Grid

Because of precession, the earth rotation axis is changing which means that the celestial north and south of the Equatorial coordinate system is changing accordingly. For this reasons sky atlases uses a reference time for this coordinate system. J2000 means the Equatorial coordinate system at the year 2000 AD.

Equatorial Grid, Year 2000. Notice the position of celestial north pole relative to Polaris.

Equatorial Grid, Year 1000. Notice the position of celestial north pole relative to Polaris.

Equatorial Grid, Year 3000. Notice the position of celestial north pole relative to Polaris.

Azimuthal Grid

This grid will display the lines of the Horizontal coordinate system  that uses the observer's local horizon as the fundamental plane. The Altitude is the angle above or below the horizon while the Azimuth is the angle from north increasing towards the east direction.


Galactic Grid

The Galactic grid will display the lines of the galactic coordinate system (GCS) is a celestial coordinate system which is centered on the Sun and is aligned with the apparent center of the Milky Way galaxy. The "equator" is aligned to the galactic plane. Similar to geographic coordinates, positions in the galactic coordinate system have latitudes and longitudes. The northern galactic pole is located in the constellation of Coma Berenices while the southern pole lies in Sculptor.


Equator Line

The equator line is the line with declination 0° in the equatorial coordinate system. It is a projection on the celestial sphere of the earth equator.


Meridian Line

The meridian line is the line with azimuth 0° in the horizontal coordinate system. It is a great circle passing by the north and south points of the local horizon, the north celestial pole and the observer zenith.


Horizon Line

The horizon line defines the local horizon of the observer. It is the line with altitude 0°.


Ecliptic Line

The ecliptic line is the line defining the sun apparent path against the stars.


Galactic Plane Line

The galactic plane line is the line with zero longitude. It defines the disk plane of the galaxy. You will find it aligned with the milky way.


Cardinal Points

This option will show or hide the four cardinal points, North, East, South and West.

Constellations


Show lines

Lines that define the constellations figure by connecting some of its star members. You can also display the lines through the shortcut key [C] or through the horizontal bar button .

Show labels

Displays the names of the constellations. You can also display the labels through the shortcut key [V] 

Show boundaries

Show the boundaries of the constellations as defined by the IAU. This option is applicable to the Western sky culture only.

Show art

This option will display the constellation figures as imagined by the respective culture selected from the list under the Star lore tab.  You can also display the figures through the shortcut key [R] or through the horizontal bar button 

Art brightness

Set the value for the desired brightness of the constellation figures.

Constellation figures, labels, lines and boundaries are displayed

Projection

Projection here means the method of representing the celestial sphere on a flat display screen. Different projections exist and each will have some distortion of the real 3D celestial sphere. Stellarium gives you the freedom to select from different types of projections to suit you viewing needs.


Perspective

Perspective projection keeps the horizon a straight line. The mathematical name for this projection method is gnomonic projection.

Maximum FOV: 120°

Equal Area

The full name of this projection method is, Lambert azimuthal equal-area projection. It preserves the area but not the angle.

Maximum FOV: 360°

Stereographic

Stereographic projection is known since the antiquity and was originally known as the planisphere projection. It preserves the angles at which curves cross each other but it does not preserve area.

Maximum FOV: 235°

Fish-eye

In fish-eye projection, or azimuthal equidistant projection, straight lines become curves when they appear a large angular distance from the centre of the field of view (like the distortions seen with very wide angle camera lenses).

Maximum FOV: 180°

Hammer-Aitoff

The Hammer projection is an equal-area map projection, described by Ernst Hammer in 1892 and directly inspired by the Aitoff projection.

Maximum FOV: 360°

Cylinder

The full name of this projection mode is cylindrical equidistant projection. With this projection all parallels are equally spaced.

Maximum FOV: 233.333°

Mercator

The mercator projection is one of the most used world map projection. It preserves direction and shapes but distorts size, in an increasing degree away from the equator.

Maximum FOV: 233.333°

Orthographic

Orthographic projection is related to perspective projection, but the point of perspective is set to an infinite distance.

Maximum FOV: 180°


A sample sky map using equatorial mount mode with Hammer-Aitoff projection option.

Landscapes 

Landscapes are the scenes used for ground in Stellarium. You can select a landscape from the list on the left side of the window.



From the information displayed on the right side, you will find that each landscape is associated with a planet and  a specific location (latitude and longitude). The selection of the landscape will not alter your set location unless you check the "Use associated planet and position" box.

Garching landscape                                                           Ocean landscape

Options

Show ground

Check the box to show the landscape (ground). If unchecked, objects below horizon will be visible. You can also toggle ground on and off by using the ground button from the lower horizontal bar or by the key [G].

Ground on                                                                                        Ground off - Saturn below horizon

Show fog

If checked a band of fog will be displayed along the horizon. You can use the key [F] to toggle fog on and off.

Use associated planet and position

If checked the landscape planet and position will be used as the location of the observer. 
The information with the selected landscape has the details of its planet and location.

Use this landscape as default

If checked, this landscape will be the landscape Stellarium uses at startup.

Add/Remove landscapes

Note: This procedure is from Stellarium wiki, landscapes

At the bottom of the Landscape window, there is a button which enables you to add more landscapes.



By pressing the add/remove landscapes button, the following dialog appears:



This allows you to install.zip files containing landscapes. It also lists the user-installed landscapes and allows you to remove them.

You can download .zip files containing landscapes from Stellarium wiki page User Contributed Landscapes (by continent).

Note that while this makes installing landscapes easier, it may also cause you to overlook what else is included in the ZIP archive. Landscape packages created without this feature in mind may contain other files, such as alternative textures in different sizes. 

Starlore 

Different people viewed the sky and the patterns of the stars differently. Stellarium provides 14  sky cultures. Each one has a distinctive set of constellations and star names. Western sky culture has the 88 constellations recognized by the International Astronomical Union.


When you select a sky culture, information about it is displayed and you can set it to be your default sky culture that Stellarium uses at startup by checking the box "Use this sky culture as default".



Arabic sky culture with Greek influence


Western sky culture