User:Praemonitus/Astronomy style guide

This draft subpage of the Manual of Style contains guidelines for writing and editing clear, encyclopedic, attractive, and interesting articles on astronomy. For matters of style not treated on this subpage, follow the main Manual of Style and its other subpages to achieve consistency of style throughout Wikipedia.

Naming conventions
Articles about astronomical objects should use conventional astronomical naming conventions for the article title, particularly as specified by the International Astronomical Union. In most cases, proper names should only be used when they satisfy WP:COMMON NAME.

For catalogue names, standard astronomy abbreviations can be used. Hence, BD instead of Bonner Durchmusterung and GJ rather than Gliese–Jahreiß. The exception is the Bayer designation of a star, which uses the fully Latinized greek letter followed by the genitive form of the constellation name. An example is Sigma Orionis, for σ Ori.

For components of multiple star system, the convention is to follow the system name by a capital letter. Thus, Alpha Centauri A and Alpha Centauri B. Exoplanets typically use a lower case letter, such as Epsilon Eridani b.

Capitalizing object names
The capitalization of specific astronomy objects is discussed at: MOS:CELESTIALBODIES. The universe, including the visible universe, uses lower case, except when discussing it in its entirety, such as in a multiverse context.

Images
An astronomical image is any image file concerning non-artificial objects or phenomena that originate outside the Earth's atmosphere. It can include photographs, diagrams, and illustrations. In addition to the usual standards of image selection outlined by the Image use policy and Manual of Style/Images, which cover image quality and pertinence, other considerations apply to articles about astronomy:


 * Wherever possible, the lead image in an astronomy article should show the object as viewed in natural light, without enhancements of specific spectral bands or frequency shifting. Usually this means an image taken in the V-band of the UBV photometric system. This may not be possible for heavily redshifted or dust-obscured objects, in which case an infrared image will serve. If the lead image has been modified or enhanced, it should state this in the caption.


 * Any diagrams should include a reliable source for the data used to create the diagram. In most cases, SVG format is preferred for this type of illustration.


 * Restrictions on the use of artistic illustrations are discussed at WP:ASTROART

Units
Per the manual of style policy, the conventional units for astronomy science articles are SI and these should be used consistently throughout an article. Astronomy uses certain unit conventions for specific parameters, and these take primacy where appropriate:
 * AU is an acronym for 'astronomical unit' and is used for distances on the scale of a stellar system. Per SI convention, it can also be listed in lower case as 'au'.
 * Large distances are given in units of light years (ly) or parsecs (pc), rather than metres.
 * Density is usually given in cgs.
 * The masses and radii of large astronomical objects are listed relative to the same quantity for the Sun, Jupiter , Earth (M🜨, ), or the Moon . Luminosities are listed relative to the Sun.
 * Ages are in Myr or Gyr.

Infoboxes
All object-specific infobox data should have inline references specifying reliable sources. Database sources such as SIMBAD and NED are invaluable sites for finding reliable sources. However, in general they should not be cited as a source for the infobox data because the information is subject to change over time and comes from multiple overlapping sources. However, they are useful as a stable reference for the other designations listing.

Whenever the coordinates of an astronomical object is included, it should also list an epoch so the date context is clear. Typically this is J2000.

Providing error ranges gives the reader a useful indication of the accuracy of the data. In most cases where an error range exists, there is little need to retain accuracy beyond the first two or three digits of the error margin. For example, $48.805$ can be listed as $48.8$.

In some instances, different reliable sources may give data values with error ranges that do not overlap. It may be of interest to provide two or more such data values in the infobox, if this is believed to be of interest to the reader. The values should be separated by a comma or a new line, and include the margins of error.

There is a set of standard infoboxes for astronomical objects and associations of different types:


 * All galaxy types use Infobox galaxy. Groups and clusters of galaxies use Infobox galaxy cluster.
 * Open clusters use Infobox open cluster, while globulars use Infobox globular cluster.
 * Moving groups and stellar associations use Infobox stellar association.
 * All nebulae use Infobox nebula.
 * Planets, exoplanets, and minor planets use Infobox planet.

Stars
Stellar articles generally include an infobox consisting of templates from the starbox group. These start with the Starbox begin and continue to the Starbox end. Typically they will include the Starbox observe, Starbox character, Starbox astrometry, and Starbox catalogue templates. When a star has more detailed parameter information, Starbox detail can be included after the Starbox astrometry template. For multi-star systems, the Starbox orbit and Starbox relpos templates are available.

For stars that are visible to the naked eye, a location chart may be included at the top of the infobox using the Starbox image template. These generally use an appropriate constellation map, available from the Wikimedia commons. The Location mark template is recommended for overlaying a marker identifying the star, as it provides consistent positioning accuracy. See the starbox image template documentation for further information.

The odlist template is strongly recommended for formatting the entries in the Starbox catalogue template. The 'name=' field can be used for a proper name.