CITE THIS NOTEBOOK: Wolfram R&D LIVE: Introducing Astro Computation by José Martín-García. Wolfram Community MAR 16 2023.

AstroPosition

• Find the coordinates of a celestial object:
AstroPosition
Mars
PLANET

AstroPosition
Azimuth: 57°8'34.0"
Altitude: 1°35'39.5"

• Use any celestial frame:
AstroPosition
Rigel
STAR
,"Equatorial"
AstroPosition
Right ascension:
h
5
m
15
s
38.9
Declination: -8°10'39.0"

• Use any coordinate system:
AstroPosition[Here,"ICRS","Cartesian"]
AstroPosition
X coord: -0.94306au
Y coord: 0.302557au


AstroGraphics

• Show a region of the celestial sky:
AstroGraphics
Scorpius
CONSTELLATION
,AstroReferenceFrame->"Equatorial"
• Jupiter and Venus are currently close to each other:
AstroGraphics
Venus
PLANET
,AstroReferenceFrame->{"Horizon",DateObject[{2023,2,28,19,0,0}]},AstroRange->
10
°

• Or the whole sky, in the galactic frame:
AstroGraphics[AstroReferenceFrame->{"Galactic",Now,Here},AstroBackground->"GalacticSky"]

Outline

◼
  • 0) Simple examples
    • ◼
  • 1) Reference frames and time systems
    • ◼
  • 2) AstroPosition
    • ◼
  • 3) Astro computation
    • ◼
  • 4) AstroGraphics
    • ◼
  • 5) Application examples
    • ◼
  • 6) Constellations
    • ◼
  • 7) (Future) 3D visualization

    • 1. Reference Frames and Time Systems

    1.1. Main Families of Frames

    ◼
  • “Equatorial”: use Earth’s equatorial plane.
    • ◼
  • “ICRS”, “J2000”, “GCRS”, “TETE”, “MEME”, “CIRS”.
    • ◼
  • “Ecliptic”: use Earth’s orbital plane.
    • ◼
  • “TrueEcliptic”, “MeanEcliptic”.
    • ◼
  • “Galactic”: use Milky Way’s plane.
    • ◼
  • Co-rotating with Earth: “TIRS”, “ITRS”.
    • ◼
  • “Horizon” frames: use local horizontal plane.

    • 1.2. Time Systems

    Possible cases:
    ◼
  • Atomic time at the surface of the Earth.
    • ◼
  • “TAI”, “TT”, “UTC”
    • ◼
  • Time determined by the rotation of the Earth.
    • ◼
  • “UT1”
    • ◼
  • Time at places other than Earth surface.
    • ◼
  • “TCG”, “TCB”, “TDB”, ...
    • Examples:
    Orange: TT - UT1 ± 0.9s, Blue: TT - UTC

    2. AstroPosition

    2.1. Main ideas

    • Follow GeoPosition:
    ◼
  • coords is a coordinate array.
    • ◼
  • frame is “Equatorial” or {“Equatorial”, date, loc, ...}, etc.
    • ◼
  • csys is “Cartesian”, “RADec”, “LonLat”, ... or a projection.
    • • Example: Observe the Moon’s center from your location:
    • Angles are stored as degrees, distances as astronomical units:
    • Coordinate conversions for that same date and location:
    • Dynamic motion of the Moon:
    • Extract properties:
    • Directions in space:
    The true equinox is the X axis of the TETE and TrueEcliptic frames:
    This is a consequence of precession:
    This is a consequence of nutation:

    2.2. Example: Observe Here from the Moon

    • Observe our location from a point on the Moon:
    Define this function that takes any day d in March 2023:

    3. Astro Computation

    3.1. AstroDistance

    • Compute the current distance to an object from your location:

    3.2. AstroAngularSeparation

    • Angular separation between two objects as seen from a third (your local position by default):
    • Find the closest approach between Jupiter and Saturn in 2020:

    4. AstroGraphics

    4.1. Maps of the whole sky

    • Use other frames:
    • Choose your own projection for any frame:
    • And a background image:

    4.2. Maps of local regions of the sky

    • Specify an object and give an angular radius:
    • Again, we can add the background image:
    • Show the area of the Andromeda galaxy:

    5. Application Examples

    5.1. Zoom in around Jupiter

    5.2. Retrograde motion of Mars

    • Take a collection of weekly positions of Mars over a year, with a background of today:

    5.3. Solar eclipses

    • Eddington's observations of gravitational light deflection:
    Visualize what happened during the eclipse, centering around the position of the Sun:
    • Annular eclipse next year. Notice how in this case the Moon looks smaller than the Sun.

    6. Constellations

    • This is the sky around the North Celestial Pole:
    • Activate constellation illustrations:
    • Use styling options for full control:

    Conclusions

    ◼
  • New Astro project in 13.2. Experimental status.
    • ◼
  • AstroPosition describes observations of anything from anywhere any time.
    • ◼
  • AstroGraphics shows maps of the sky in several frames and projections.
    • ◼
  • There is still much to do:
    • ◼
  • Velocities, orbits and orbital elements.
    • ◼
  • All about eclipses, occultations, transits and other events.
    • ◼
  • More data, more types of charts and 3D visualization, more computational functions, ...