Mars, Spica, and Uranus

   And before you say it John, it does not continue with “walked into a bar.”
   On Tuesday 25 March two of the outer planets, Mars and Uranus, will be at the position along their respective orbital path where they are on opposite sides of the Sun from each other. This is called a heliocentric opposition and is based on using the heliocentric coordinate system. This is essentially a horizontal system of 0-360 degrees as measured eastward around the Sun. Mars has a heliocentric longitude of approximately 192o compared with Uranus’s heliocentric longitude of 12o. If nothing else what I think is interesting is how the orbits of these two planets compare with each other. The banner graphic at the top of the page shows the radius of each each planet’s orbit. Mars is 1.6 AU from the Sun, while Uranus is 20.0 AU from the Sun.

Click on graphic to see it full size.

Click on graphic to see it full size.

   Easily visible in the pre-dawn skies is Mars, its nearby stellar companion, the bluish-white star Spica, the planets Saturn and Venus, as well as several bright stars of the late northern hemisphere summer season.

Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

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