Night mode offers a wealth of photographer-relevant information about the night sky. There's quite a lot packed in there, so here's a handy guide to use it:
A symbolic representation of the Milky way is shown in Night Mode. The central band of the Milky Way is shown as a ring of spheres, which increase in size and brightness towards the galactic centre.
You can determine the azimuth and altitude from the red pin position to the galactic centre from the altitude chart legend below the timeline. In addition, the angle formed by the arch of the Milky Way relative to the horizon is labelled directly on the map (e.g. +68.3° in the example shown above).
The Milky Way is a spiral galaxy, that is array as a flat disk with a central bulge. Earth lies near the central plane of the Milky Way, but away from the centre. As a result, the Milky Way is observed as a band in the sky with brighter region towards the galactic centre.
Note: In far northern latitudes, the Galactic Centre is never visible due to the orientation of Earth relative to the Milky Way. At moderate or lower northern latitudes, the Galactic Centre is visible only during summer.
The northern and southern pole stars (Polaris and Polaris Australis respectively) are displayed. Which you will see is dependent on your location. At the equator, both may be visible at certain times (typically very low on the horizon, and only visible due to the effects of atmospheric refraction, which serves to 'lift' objects higher above the horizon, optically).
The Pole Stars are useful for star trail photography: the celestial sphere appears to rotate around these stars, so locating them can help provide the centre of rotation for your star trail shots.
Major Stars and Constellations
In addition the the symbolic Milky Way representation, major stars and constellations are shown in their correct relative positions in the night sky.
The following constellations are shown: Canis Major, Orion, Ursa Major, Crux, Aquila, Aries, Cassiopeia, Cygnus, Gemini, Leo, Lyra, Scorpius, Taurus, and Ursa Minor.
Additionally, the very brightest stars from the following constellations are shown: Carina, Centauri, Bootes, Auriga, Canis Minor, Eridanus, Virgo, Piscis Austrinis, Sagittarius, Canes Venatici, Pegasus, Andromeda.
Tip: As drawn on the map, the constellations are viewed from "outside-in". Imagine you're on the outside of a transparent planetarium, looking in. Well-known constellations and star patterns such as Orion, Crux (Southern Cross), and the Plough (Big Dipper), should be easily recognisable.
Tap a star to see its common name, Bayer designation and current azimuth and apparent alititude (calculated for the current date/time, latitude and longitude). When you tap the star it momentarily increases in size for ease of identification. The color of the star can be observed: the color is derived from the star's B-V index. For example, Betelgeuse, a red giant, appears with a disinctly yellow-reddish hue.
The Bayer designation for a star is formed of a greek letter (α, β, γ, where α is the brightest star in the constellation), followed by the constellation name (in the Latin genitive form), e.g. Sirius is known as α Canis Majoris, the brightest star in Canis Major.
Asterisms are easily recognized patterns of stars used by astronomers to locate particular regions and objects in the sky. An asterism may be made up of a subset of stars in a constellation (such as the Plough or Big Digger), or may be formed of stars from multiple constellations (such as the Great Square of Pegasus, which includes the star Alpheratz from the constellation Andromeda).
The following asterisms are displayed in Night Mode:
- Summer Triangle
- Big Dipper or Plough
- Little Dipper
- Great Diamond
- Great Square Of Pegasus
- Winter Triangle or Great Southern Triangle
- Winter Hexagon
Tip: If you want to locate the Galactic Centre in the sky during twilight when it's still too light to see the Milky Way clearly (e.g. to set up for a shot in advance), the Teapot of Sagittarius is a useful pointer: the band of the Milky Way appears as 'steam' emerging from the spout of the teapot, with the Galactic Centre located close to the tip of the spout.
You can check the alignment of the teapot to the Milky Way using the asterism visualization in TPE.