Follow the Arc

The ‘Evening Arc’

   There is an ‘old’ Astronomical saying, a sort of memory aid, for finding at least two constellations by way of their alpha, or brightest star in their respective constellation. In Bootes the Herdsman there is the orange-reddish star Arcturus, and in Virgo the Harvest Maiden the bluish-white star Spica. The saying – “follow the arc to Arcturus, then speed to Spica” is how you connect these two stars with the curve, or arc, in the handle of the Big Dipper. Simply look toward the north to find the 7 stars making up the Big Dipper, look for the curved handle and follow the arc or curve toward Arcturus and then continue on to Spica. This is typically done during the Northern Hemisphere spring and summer season when Bootes and Virgo are in the evening skies. However you can start this observation at sunset by looking northwest for the Big Dipper and then toward the southwest for the star Arcturus. Do this early enough as Arcturus sets about an hour after sunset and in the next couple of weeks Arcturus will become too close to the Sun and will not be visible again until later during the winter as a morning visible star.

The ‘Morning arc’

   And you could continue this observation the following morning as this part of the sky rises before the Sun and you trace out the arc passing through Arcturus and ending at Spica. As the ‘Morning Arc’ graphic shows the planet Venus is close to Spica.
   Keep an eye on this part of the sky as later this month the planets Saturn and Mercury start becoming visible before sunrise. On the 26th Venus will be very close to Saturn. As the graphic shows the two planets will be close enough for both to fit within the field of view of binoculars.

Click here to go to the Qué tal in the Current Skies web site for more observing information.

One thought on “Follow the Arc

  1. Pingback: Mars – Spica Conjunction | Bob's Spaces

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