Sunday, January 19, 2025

Six planets

 Aside from the moon, the four brightest objects in the night sky right now are:

  1. Venus, mag -4.5
  2. Jupiter, mag -2.4
  3. Sirius, mag -1.4
  4. Mars, mag -1.3,

and they are all visible at the same time in the evening sky.  In addition to the three bright planets in this list, three more are also visible.  Saturn, at mag 1.1 is easy to see only 2.2 deg from Venus. Uranus is almost directly overhead.  At mag 5.7 it is theoretically visible to the unaided eye, if you have young eyes and are in a dark-sky location.  It is easy to see with binoculars.  Neptune is in the western sky with Venus and Saturn.  At mag 7.9 it requires big binoculars (e.g. 7x50 or larger) and the end of twilight.

Neptune, Saturn, Venus.  Sigma 30mm f/1.4 @ f/1.6 + softon filter. ISO 800, 10 s.

Neptune.  Olympus 75mm f/1.8 @ f/2.5.  ISO 800, 10 s.

Saturn and Venus.  Olympus 75mm f/1.8 @ f/2.0. ISO 800, 6 s.

Jupiter, the Hyades, the Pleiades, and Uranus.  Sigma 30mm f/1.6. ISO 800, 10 s.

The Pleiades and Uranus.

Castor, Pollux, and Mars lined up.  Sigma 30mm.  ISO 800, 15 s.

Castor, Alpha Geminorum, is an attractive double star for small telescopes.  The two components are currently separated by about 5.5 arcsec and orbit their common center with a period of 459 years [Guillermo Torres et al 2022 ApJ 941 8].  Each star is also a spectroscopic binary, making this a quadruple-star system.

Castor A + B.  Sky-Watcher SkyMax 102 MCT+ E-M5iii + Tele Vue 2.5x powermate.  Stack of two images: ISO 200, 1/2 s + ISO 400 1/3 s.

There is also a third fainter visual component, Castor C (not seen here), which is itself a spectroscopic binary.  Castor is therefore, in total, a six-star system.

Orion is always an irresistible photographic target.

Neptune, Saturn, Venus,  Sigma 30mm, no filter.



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