Thursday, March 15, 2012

Venus-Jupiter Conjunction


The planets Venus and Jupiter will be in conjunction on March 15th, 2012, appearing to pass within 3° of each other in our nighttime sky. The two planets have been getting gradually closer in our sky for the last month. Venus is the higher, and brighter object, and Jupiter is the lower and dimmer one.


The above image depicts the western sky on March 15 around 9 PM Daylight Time (8 PM local time). The two planet symbols in the center of the image represent the positions of Jupiter and Venus. Jupiter is the gold symbol on the left and Venus is the blue-and-white symbol on the right. The outlines of the surrounding constellations are marked and labeled. In addition, above the planets is marked the location of M45 (Messier object 45), a small cluster of stars that is also known as the Pleiades. (The image was produced using Your Sky software by John Walker, available online at www.fourmilab.ch/yoursky/ )

Of course, Venus and Jupiter are really separated by millions of kilometers (Venus orbits the sun closer than Earth, and Jupiter orbits much farther away than Earth). But from our perspective on Earth, we see the two objects closely aligned. This alignment is called a conjunction.

On March 15th, 2012 at 10:37 UTC, Venus and Jupiter reach 3° distance from one another. That’s approximately 6 times the width of the full Moon (or six times the width of your extended thumb).

The conjunction will be visible from everywhere on Earth. The two planets will brighten in the West shortly after sunset. And because Venus and Jupiter are two of the brightest objects, they will be visible even in the most light polluted (brightly lit) cities.

As a special bonus, the planet Mars is also high and bright in the sky, visible as that bright red “star” further to the East. Mars recently reached its closest point to Earth, known as opposition. Mars won’t be this close and bright for two more years.

And on March 25th, 2012, the New Moon will join the pair again to create a triple conjunction. Another great photo opportunity.

A visual separation of 3° sounds close, but these planets can actually appear much closer. For example, on October 26, 2015, the two planets will appear to be only 1° apart. But our current Venus/Jupiter conjunction is one of the best we’ll see for a few years because the two planets are so high in the sky after the Sun sets.

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