Mercury: less than a degree from Mars

Event Date: February 7th

Time: 6:00 PM

Brief

   This evening and next, I will highlight the Mercury/Mars encounter, as the two come close low and seen in the west-southwest.  Tomorrow is when we see them closest at our longitude (did you predict that correctly, as I encouraged you to last week??), although they are still impressive seen at this current separation of 0.6º.  That is slightly more than the angular size of the Moon at perigee, by a couple of arc-minutes.  The next time you see the Moon full at perigee, think of a line slicing it exactly in half, with each planet on opposite sides of the Moon's circumference, and that close to how we see them this evening separation-wise.  At magnitudes -1.0 and +1.2, Mercury and Mars are shown below at those respective magnitudes.  The following images are of a zoom-out and then a 2º zoom-in, also showing their orbits.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   In the second image above, the orbits are shown dimly, to indicate that both planets are on the "far" side of the Sun, as seen from Earth.  Mercury has not yet reached greatest western elongation, which is about the time that we are about the same distance from both it and the Sun.  As for Mars, it is getting close to conjunction and therefore, much further from us than when at opposition.  What is more impressive when looking at the orbits, is that just below the field of view indicator, they come close to meeting with each other.  If the planets had their closest conjunction at this point, closer-to-us Mercury (angular size 5.7 arc-seconds) would occult further Mars (4.1 arc-seconds).  Although Mars is larger than Mercury in diameter by almost 40%, it is also nearly twice as far from us as Mercury right now; hence, the larger angular size for Mercury.  Although no occultation this time, tomorrow evening will be a fun viewing!  Hope for clear skies, and as always, stay away from obstruction for that direction of the sky, to see them.