more on Mercury and Asellus Australis: closer

Event Date: August 19th
Time: 5:30 AM


Brief

   Yesterday, I showed Mercury near the star Asellus Australis.  This morning, the planet appears slightly brighter and closer to the star: a separation of 22 arc-minutes.  At apparent magnitude -0.4, we can magnify the rising pair to over 100x with a field large enough to fit them: 1/2º, although a full degree of field makes them appear more centered to the eye, not having to look close to the circumference of the field.
   The first image shows it and the star zoomed out, while the second image shows a zoom in of a 1/2º field to see the pair more easily at a magnification of slightly over 100.  If you want to magnify it more, you can; just keep in mind that since it is still within atmospheric pollution, that such will be more evident when viewing it, and Mercury may not appear as steady. 

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

Detailed

Use a telescope of at least 4", allowing for a magnification boost.  There is no need to have a telescope so big that it takes awhile to set up; Mercury is for the most part, featureless, looking like a dull version of our own Moon.  Of course, being much further away than our Satellite, at about 92 million miles right now from us (slightly under one a.u., being just past greatest elongation) Mercury is hundreds of times further than our Moon at its mean distance.
   Shortly after 10 AM, which is dawn for viewers in the far east, the two are at their closest at slightly 15 arc-minutes.  Viewers in Australia and New Zealand can see this too, although the geometry of their morning sky is much worse than ours at this time of year, and they will have to look more towards the horizon.  However, they don't have to be as concerned about morning twilight lasting long, being late winter down there.  Although we miss the closest encounter, we still get to see Mercury pass by several stars--some brighter than others--during this fine, late summer apparition.  Look forward to Mercury continuously growing brighter between now and when we start to lose it to the glare of the Sun shortly before superior conjunction next month.