Event Date: August 9th
Time: 5:45 AM
Brief
Mercury is now visible to the eye alone, as it has brightened quickly. When we saw it emerging from the Sun's glare in retrograde about a week ago, we saw it only as a thin crescent. Despite the good geometry of the eastern sky at this time of year, it wasn't enough light reflecting back to our eyes, from the small planet. Now as Mercury waxes, currently at 18% illuminated, that has helped see it better. Keep it mind that since Mercury is so much smaller than Venus and its orbit doesn't bring us as close to it during inferior conjunction, it brightens and dims quickly, for waxing and waning respectively. Here it is shown in orbit about 40 minutes before Sunrise.
Time: 5:45 AM
Brief
Mercury is now visible to the eye alone, as it has brightened quickly. When we saw it emerging from the Sun's glare in retrograde about a week ago, we saw it only as a thin crescent. Despite the good geometry of the eastern sky at this time of year, it wasn't enough light reflecting back to our eyes, from the small planet. Now as Mercury waxes, currently at 18% illuminated, that has helped see it better. Keep it mind that since Mercury is so much smaller than Venus and its orbit doesn't bring us as close to it during inferior conjunction, it brightens and dims quickly, for waxing and waning respectively. Here it is shown in orbit about 40 minutes before Sunrise.
Detailed
Mercury rises 70 minutes before the Sun this morning. Although the upcoming greatest elongation is one of which Mercury doesn't appear to separate from the Sun much, the declination gap between the two is slowly growing. Therefore, with Mercury separating from the Sun and a bigger rise time-gap each morning in compared to the Sun's, the sky is darker to see Mercury more easily each evening until it gets too close to superior conjunction in early September. A small number of days before then, the Sun is moving south towards the celestial equator at almost its fastest of the year, making still-brightening Mercury a good target for morning viewing. It will not get as bright as Jupiter high above it, and Venus (both unlabeled) between the two being even brighter. However, looking on the other side of east towards Canis Major a bit south of that is, Sirius (-1.5) is dimmer than Jupiter, and will be rivaled by Mercury in early September shortly before superior conjunction lower towards the horizon. Whereas Sirius' light will refract through the atmosphere, making its own light, Mercury's reflecting of light will cause it to look still, without a fierce twinkle of many colors as Sirius will have for some minutes during twilight. As the second image shows, shifted more towards the southeast, we see Sirius now low towards the horizon. several minutes before the Sun comes up.
Much dimmer Procyon, the "brightest" star of [little dog] Canis Minor, is seen between Mercury and Sirius. I will get more into Canis Minor as the season progresses. However, if you remember my Winter Circle entries from the late winter and early spring when it was high enough to see in the west, I mentioned the Procyon then.
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| click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
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