You are hereTHIS MONTH’S SKY - May 2012



Celestial Events -- May 2012


Venus has dominated the western sky for months, but this is about to come to an end. On May 1st it is still 36° above the Sun. By midmonth this is down to 28°, and at the end of May it is only 6° from the Sun and no longer visible. Chart 1 to the right shows the dramatic movement of Venus.

What is happening is Venus is close to Earth, so its motion is exaggerated from our viewpoint. The table below indicates the changes in our view. Note that during May Venus's size grows, while its phase (percent illuminated) shrinks.

On June 5th in the late afternoon, we will see a rare event. On that date we will be able to observe Venus passing in front of the Sun. The event, called the transit of Venus, is extremely rare -- usually Venus passes above or below the Sun. The transit occurs only when Earth, Venus and Sun lie in the same plane. The last transit of Venus occurred on June 8, 2004, and the next one will come on December 11, 2117.

For those in New York City, the transit will begin late in the afternoon at 6:03 PM and continue until sunset at 8:23 PM.

Chart 1. Venus' position in the evening sky in May

Venus' Data

  Magnitude Elongation
From Sun
Diameter Illumination
May 1 -4.7 36° 37.4" 27%
May 16 -4.6 25° 47.0" 12%
May 31 -4.1 6° 56.7" 1%




Click to get sky charts and a description of the sky for this month.


MERCURY is poorly placed in the pre-dawn sky. You might see it with binoculars in the first week of May. It will be at superior conjunction on the 27th, entering the evening sky.

VENUS (magnitude -4.7 to -4.1, diameter 37.4" to 56.7", illumination 27% to 1%) has been dominating the western sky for months. See above.

MARS (magnitude -1.2 to -0.7, diameter 13.8" to 12.6"), in Leo, is at opposition from the Sun and up all night on the 3rd.  Two days later it is closest to Earth. (Because Mars' orbit is an ellipse, not a circle, the events don't occur on the same day.)  This is a great time to view the red planet with a telescope.

JUPITER (magnitude -2.2 to -2.1, diameter 36.1" to 33.9") is in Aries. Jupiter spectacularly meets Venus on the 13th (see VENUS above).

SATURN (magnitude +0.4 to +0.3, diameter 18.4" to 19.0") remains in Virgo, near the bright star Spica. It is retrograding in preparation for its opposition from the Sun on April 15.

URANUS (magnitude +5.9, diameter 3.3") is too close to the Sun to be seen. It is in conjunction with the Sun on the 24th.

NEPTUNE (magnitude +8.0 to +7.9, diameter 2.2") is too close to the Sun for most of the month, but can be seen later in the morning sky with a telescope.

PLUTO (magnitude +14.1, diameter 0.1") is in Sagittarius, too near the Sun to be seen.

See below for phases of the Moon and the Moon's conjunctions with planets and bright stars.

(Times in EDT)

May 4 Moon, Saturn and Spica gather low in the evening sky. Mars and Moon are 6½° apart, Saturn and Moon are 8½°.
May 5 Eta (η) Aquarid meteors peak (but Full Moon will limit the number seen).
  Full Moon at 11:35 PM EDT.
May 8 Antares is 8° below left of the Moon.
May 12 Last Quarter Moon at 5:47 PM EDT.
May 13 Jupiter is in conjunction with the Sun.
May 15 Venus is stationary, and begins falling back toward the Sun
May 20 New Moon at 7:47 PM EDT.
  Annular solar eclipse.  Unfortunately not visible from New York.
May 22 Venus is 5° above the Moon.
May 27 Mercury is in superior conjunction with the Sun, entering the evening sky.
May 28 First Quarter Moon at 4:16 PM.
May 29 Mars is 7° north of the Moon.