2018: The Evening Sky



July 9: Venus Passes Regulus

This article summaries the planetary activity in the evening sky during 2018.  The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):

The chart shows the setting of planets, stars, and the moon (circles) compared to sunset.  This occurs in the western sky.  The three phases of twilight are graphed as well.

Conjunctions are displayed with squares.  Yellow triangles and the letters “GE” show the greatest elongation of Mercury or Venus.  A yellow diamond with the letters “GB” indicate the interval of Venus’ greatest brightness.

The rising of Mars, Jupiter, and Saturn are displayed.  This occurs in the east.  The opposition dates of those planets are also indicated.

It is important to emphasize that the chart shows setting times.  When the setting lines of two objects cross, it indicates that they set at the same time.  Because we have chosen planets and stars along the ecliptic, the virtual path along which the sun, moon and planets appear to move along, they can appear at conjunction or near each other.   This can occur within a few days of the date of coincident setting.  For the purposes of the chart, the conjunction is indicated on the setting time curve of the brighter planet.  When considering planets setting at the same time, consider this:  Sirius, the brightest star in the night sky, sets at about the same time as Aldebaran in Taurus.  The stars, though, are 46 degrees apart in the sky.  Sirius sets in the southwest and Aldebaran sets in the west-northwest.

The charts below summarize some of the evening events during the year.  This includes oppositions of Jupiter, Saturn, and Mars.  Just before the opposition of Mars, the five naked eye planets can be seen at once.  Observers at more southerly latitudes see this event easier.

Jupiter and Venus do not have a conjunction.  At the end of September the planets are closest at 14 degrees.



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