The view around us

Here is an attempt to show how several things are now arranged in space.

Space view 2016 August 20

In this three-dimensional picture, from a viewpoint 15° north of the ecliptic plane, the paths of the planets are shown for August.  The Sun is exaggerated 5 times in size, the inner planets 400 times, Jupiter 50 times.  Sightlines from Earth are at Aug. 20.  The dashed line is the vernal equinox direction.

The planets appear to the east of the Sun, that is, in the evening sky, as we have been seeing, Because Mercury is (from our point of view) slowing toward its curve back westward, it appears to approach as near as 3.8 degrees to Jupiter on Aug. 20 but has no conjunction, falling away sunward.

In this wider view –

Space view 2016 August 20, wider

– appear two minor bodies which happen to be now at their best (though not very good) situations for the year.  Their paths are drawn for the three months July-August-September.  The “stalks,” by which I show how far the bodies are north or south of the ecliptic plane, are more obvious for these ones, which don’t keep close to that plane as the planets do.

Periodic Comet 43P Wolf-Harrington is at perihelion, its nearest to the Sun, on Aug. 19, but (as explained in the “Comets” section of Astronomical Calendar 2016) it’s not a favorable perihelion: the comet is far ahead of us, in the morning sky, as dim as magnitude 11.5.  It descended through the ecliptic plane on Aug. 4.

Chart for Comet 43P Wolf-Harrington

Asteroid 2 Pallas is at opposition on Aug. 20.  It is the major asteroid with the remarkably tilted orbit, so that it now appears far north of the ecliptic (not so far north of the celestial equator), in Pegasus.  It is about at magnitude 9, still far below naked-eye visibility.

Chart for asteroid 2 Pallas

So these, unless you have a fine telescope, are sights only for contemplation, but that contemplation can be quite vivid.  Use the Moon as a guide; two days past Full, it is south of the Great Square of Pegasus.  Pegasus extends west (right) from the Square.  As we on our smaller orbit overtake Pallas, you can imagine that dark 325-mile-wide rock seeming to move back from the constellation of the Flying Horse into the constellation of the Little Horse (Equuleus), nearer to the Milky Way.


3 thoughts on “The view around us”

    1. Temporary constellations! Temporary asterisms!
      I’m imagining a signal coming to us from an exo-civilizations that way, instead of by patterns in the digits of pi.

  1. Guy, thanks for the sightline diagrams and the description of the planets motion through the month. At the risk of becoming tiresome, I noticed another obvious temporary constellation / asterism last night (August 20) while looking at the Mars / Saturn environs. The pattern made by Antares, Mars, Saturn, and Delta Scorpii looked remarkably like an expanded version of the Water Jar in Aquarius, that slightly off-kilter three-vaned pattern in the northern part of that constellation. This one was a lot brighter! Something like this:





    Drawing patterns in your comments box probably doesn’t work too well, but in the sky it was striking!

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