March 25, 2017

Astro-Event of the Week:03.23.09:Can you spot Venus at Inferior Conjunction?

Warning: Do not attempt this weeks’ astro-feat unless the Sun is properly blocked, preferably just below the horizon! Sweeping the area near the Sun with optical equipment introduces the very real possibility of momentarily pointing at the Sun, which can cause optical damage!

inferior conjunction

Venus at Sunrise, as seen from Bangor, Maine, March 27th. (Credit: Stellarium).

This week’s observing challenge is a unique attempt, and will put you in league with a handful of skilled observers that even realize this is possible. It is not generally appreciated that Venus’s orbit is tilted 3.4 degrees in relation to our own, as represented by the ecliptic. As bright as Venus is, this means that on occasion, Venus can be sighted during inferior conjunction when it passes between the Earth and the Sun! Such an event occurs Friday, March 27th, 2009. With the passing of the Solstice last week, geometry favors a sunrise sighting. In the southern hemisphere, the reverse will be true. Venus will be an extremely slender crescent, (59 arc seconds in diameter, and 1% illumination) and about 5-10 degrees above the horizon slightly before local sunrise. The farther north you happen to find yourself, the better your chances of viewing success. I first completed this challenge from North Pole, Alaska, during the Inferior Conjunction of January 16, 1998 about 7 hours and 45 minutes past conjunction. Sweeping the dawn horizon with binocs will help with the initial sighting; once you know its exact position, you’ll be surprised how easy Venus is to spot with the naked eye. This year, I find myself in sunnier climes (Hudson, Florida) and Venus will be a tougher target, about six scant degrees above the horizon…good luck!

Still can’t see it? Or just plain clouded out, or want to watch indoors were its warm? Venus will be transiting through the Solar Heliospheric Observatories’ (SOHO) LASCO 3 camera around the same date… check them out on the blogroll to the right!

The astro-word of the week is Inferior Conjunction. This has nothing to do with a celestial bodies’ self-esteem; Inferior Conjunction is simply when a planet passes between the Earth and the Sun. Only two can do it; Mercury and Venus. Very rarely, we get a transit, as Venus will do in 2012. This is the last in an eight year spaced pair; by all means try to find yourselves under sunny skies, as the next transit of Venus will not occur until 2117 A.D.!


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