Event Date: August 2nd
Time: 4:00 AM
Brief
Yesterday, when showing Orion with Sirius just beginning to rise, I intentionally left off the labeling of Jupiter and Venus, so as not to distract from my topic of discussion. This morning, with Venus quickly approaching greatest western elongation, I will show it with a few number updates. Jupiter rises well before Venus now, and far separated from it, compared to a month ago when the two were only about 5º apart. Since then, Venus has waxed in phase, become a little brighter, and has moved further away from us in orbit. Although we don't really notice these features with the eye alone, a telescope magnifying it at minimum 60x can show the phase.
Here they are, with Venus' orbit showing, as well as the celestial equator and ecliptic. Notice how Venus is still on the thick (closer) section, yet moving to the thinner (further) part. The second image shows the planet zoomed in at a magnification of about 200x.
Time: 4:00 AM
Brief
Yesterday, when showing Orion with Sirius just beginning to rise, I intentionally left off the labeling of Jupiter and Venus, so as not to distract from my topic of discussion. This morning, with Venus quickly approaching greatest western elongation, I will show it with a few number updates. Jupiter rises well before Venus now, and far separated from it, compared to a month ago when the two were only about 5º apart. Since then, Venus has waxed in phase, become a little brighter, and has moved further away from us in orbit. Although we don't really notice these features with the eye alone, a telescope magnifying it at minimum 60x can show the phase.
Here they are, with Venus' orbit showing, as well as the celestial equator and ecliptic. Notice how Venus is still on the thick (closer) section, yet moving to the thinner (further) part. The second image shows the planet zoomed in at a magnification of about 200x.
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| click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
Detailed
While Venus is still two weeks from greatest elongation, it spends about a week before and after at nearly the same elongation: 45.7º. During that time, with the geometry improving in the morning for the eastern sky, its rise-gap with the Sun continues to grow quickly. The Sun continues to move closer to the celestial equator from our perspective, while Venus follows it further north. This morning for example, Venus rises at 2:58 while the Sun does at 6:13: 3 hours 15 minutes different. This gap grows slightly close to the time of greatest elongation and after it. I will mention the date when the difference is the largest. As for Jupiter, 15.4º away from Venus this morning, it now rises at 1:45 AM local daylight time, and well placed during morning twilight before the Sun's light makes it harder to see. Remember, this happens shortly after Sunrise. If you follow Jupiter during the time that twilight's later stages happen, it can be easier to continue tracking it with the eye alone, albeit a short time.
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