Mercury rivals Sirius in apparent magnitude

Event Date: August 26th
Time: 6:00 AM


Brief

   This is the best week to view Mercury before it gets too close to superior conjunction.  At magnitude -1.1 it is rising one hour, 12 minutes from the Sun.  Therefore with an unobstructed horizon, we have over 40 minutes of easy Mercury viewing between when it escapes atmospheric pollution and when the sky washes it out.  The evening sky's geometry at this time of day is nearing its best in about 6 weeks, yet until that time, good enough for watching Mercury brighten each morning.  Here it is seen just north of east, about 6º above the horizon and easily visible in this part of the sky.

Detailed

As Mercury brightens further this week, while still visible before disappearing in the Sun's glare, it begins to rival a bright star that I talked about earlier in the month: Canis Major's Sirius, at magnitude -1.5.  Mercury reaches this magnitude in a little over a week, although for the day or two before reaching the same, it will be close enough to matching Sirius that they will have similar brightnesses to our eye.  Of course, why Sirius twinkles like mad through atmospheric pollution, Mercury is reflecting our Sun's light and it comes back to us.  The second image shifts the sky further to the southeast for center-azimuth, showing Mercury and Sirius.  Of course, Venus and Jupiter are high above, making it a part of that sky quite bright full of solar system bodies and our brighest star in apparent magnitude, seen from Earth.

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