Mercury Takes the Spotlight

Sun-hugging Mercury is the most elusive of the five classical planets, but in late March and early April 2010 the little planet will be as obvious as it ever becomes for mid-northern observers. Moreover, the bright signpost of Venus will be there to point the way.

Tony Flanders
The two inner planets remain less than 5° apart from March 28th to April 12th, though Mercury fades greatly during this time: from magnitude –1.1 to +0.7, a loss of four-fifths of its light. They appear closest, 3.0° apart, on the evenings of April 3rd and 4th for North America.

The diagram at right shows the scene. Venus and Mercury are plotted 45 minutes after sunset for a skywatcher near latitude 40° north. For your date, draw a pencil line between the two planets’ curves to set the scene.

On the diagram, the planets are shown with their correct shapes and relative sizes as seen in a telescope at medium-high power. Venus is an almost full disk 10? or 11? wide. Mercury is smaller and strikingly dimmer but more interesting. It wanes rapidly from gibbous to crescent while enlarging from 5? to 10?, measured cusp-to-cusp, from March 22nd to April 16th.

6 thoughts on “Mercury Takes the Spotlight

  1. Tom Hoffeldertom hoffelder

    great article! this is surely the best opportunity for the general public to find mercury with the unaided eye, maybe ever. i think the direction should just be “west” tho.

  2. Guillermo Avello

    Desde Chile, bajo un cielo espectacular, estamos observando este espectacular fenómeno. Hay muchas fotografías tomadas para su posterior análisis con mis estudiantes. Para este año también tenemos la mejor ubicación mundial para el estudio del eclipse total solar (Julio2010)
    Guillermo Avello

  3. Vladimir Zhivotovsky

    I have sought the opportunity to pinpoint Mercury for a couple of years as I just more study astrology than astronomy and am not that “active” to get up early during chilly dawns trying to catch a glimpse of the Gods’ messenger when it rises before the Sun does..And voilà – both planets at last сan be seen just from my balcony (sure, using binoculars helps…). Thanks to S&T for info and pictures.

    Ukraine, 11 pm UT

  4. Jon

    We took in a truly wonderful planetary conjunction last evening in Omaha! There were some very light wispy clouds that obstructed after 8:50pm or so. But the show was grand!

    It’s hard to believe Mercury could be so high above the horizon! It seemed to “twinkle” quite a bit, so we almost talked ourselves into thinking it was a star. But alas, it was the fleet-footed messenger after all.

    Thanks for reading,


  5. bob kelly

    With Venus pointing the way, I could pick out Mercury even in the supermarket parking lot about 815pm Tuesday evening. Mercury is fading fast, however. As promised, it is much fainter than it was last Thursday. I managed to get a photo between cloud layers on Friday, posted at
    bob kelly
    just north of new york city, ny, usa

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