May 2014 Night Sky Calendar
FRIDAY, MAY 2: MERCURY AT PERIHELION
Of course, we'll start the show with an academic event. These 'academic events' are those that offer no visual delights whatsoever. In fact, they affect us hardly at all. However, we include them just to fill in space. Mercury is at its closest distance to the Sun during its nearly 88-day long orbit. Though Mercury will always remain the first world from Sol, its heliocentric distance varies considerably owing to its highly elongated orbit. We measure a planetary orbit's elongation (departure from circularity) with the value of eccentricity.
An orbit with a zero eccentricity is a perfect circle; An orbit with an eccentricity of 1 is a parabola. Between these values are ellipses of ever increasing elongation. Mercury's eccentricity is 0.205. This means that its perihelion (least) distance will be twenty percent less than its mean distance; and its aphelion (greatest) distance will be twenty percent more. (By comparison, Earth's eccentricity is 0.016) Mercury's average distance from the Sun is about 36 million miles; its perhelion distance today will be about 28.6 million miles.
SUNDAY, MAY 4: MOON 5.4 DEGREES SOUTH OF JUPITER (BRONZE EVENT!)
We go through this every month, it seems. At some point, the moon ventures close to Jupiter and we see them both. This month, the waxing crescent moon is less than five and a half degrees from Jupiter. We've given this not uncommon appulse the bronze medal this month because one will easily see the giant planet and crescent moon together in the western evening sky.
TUESDAY, MAY 6: MOON 6.5 DEGREES SSW OF BEEHIVE STAR CLUSTER We've lost the Pleiades, but have retained Praesepe: the Beehive Star Cluster. This nearby galactic cluster marks the center of Cancer the Crab, and is also its sole prominent feature. Unlike the brighter and less diffuse Jupiter, Praesepe will be slightly obscured by the lunar light interference. Nevertheless, an observer can see both the moon and galactic cluster throughout the evening as they descend in the western sky.
WEDNESDAY, MAY 7: FIRST QUARTER MOON
SATURDAY, MAY 10: SATURN AT OPPOSITION (SILVER EVENT!!)
May is Saturn's month. (You can probably guess this month's pick planet.) Today, Earth passes between the Sun and Saturn: a configuration called "opposition" as Saturn and the Sun will occupy opposite parts of the sky. Saturn will rise around sunset and remain visible all night. See more about Saturn in the PLANET WATCH section
SUNDAY, MAY 11: MOON 2.8 DEGREES SSW OF MARS
Mars isn't as bright as Jupiter, but it is still nearly as bright as Sirius, the night sky's brightest star. Mars also exhibits that distinctive reddish hue that allows one to easily distinguish between it and the surrounding stars. Find Mars and the gibbous moon over in the eastern sky in the evening and in the west by late evening and morning.
WEDNESDAY, MAY 14: SUN ENTERS TAURUS THE BULL
Now, spring begins in earnest. The westernmost of the winter constellations is concealed by the Sun. Taurus the Bull, associated mythologically with both the famous Minotaur and the bull that sired it, now plays host to the Sun. The Sun continues its ascent into the sky and will reach its solstice apex within five weeks. Taurus is one of the thirteen constellations through which the Sun appears to travel each year. The ecliptic constellations are TAURUS THE BULL, Gemini the Twins, Cancer the Crab, Leo the Lion, Virgo the Maiden, Libra the Scales, Scorpius the Scorpion, Ophiuchus the Serpent Charmer, Sagittarius the Archer, Capricornus the Seagoat, Aquarius the Water Bearer, Pisces the Fish and Aries the Ram. The Sun will enter Gemini the Twins on June 21st.
WEDNESDAY, MAY 14: MOON 0.56 DEGREES OF SATURN (GOLD EVENT!!!)
We're conferring the coveted gold onto this event because it is an occultation: the passage of the Moon in front of another body. Granted, we can't actually observe this passage ourselves. Only in the extreme southern hemisphere will one observe this lunar occultation of Saturn, Here, the moon will appear about half a degree from the sixth planet.
WEDNESDAY, MAY 14: FULL MOON
The Milk Moon.
The Full Corn Planting Moon
The Flower Moon
Now that winter has finally ended (allegedly), the full moon looms high over a warming land. We plant corn, harvest flowers, and prepare for the growing season. The bright moon light enabled farmers to plant well into the evening. The May full moon's name pertains to growth, warmth, loveliness, and all the others facets of a humane and beautiful world.
THURSDAY, MAY 15: MOON 8.0 DEGREES N OF ANTARES
We tend to avoid events involving the moon and bright stars. However, this time we thought it worthy of a mention. Antares is the brightest star in Scorpius the Scorpion: a prominent summer constellation. On this magical mid May day, we watch approaching summer as the moon moves near the Scorpion's heart.
FRIDAY, MAY 16: VENUS AT APHELION
Remember our discussion about Mercury? (Hint: the first entry.) Mercury reached perihelion, or its point of least heliocentric distance, on May 2nd. Venus reaches aphelion, or its greatest heliocentric distance, today. It will stray about 67.7 million miles from Sun, as opposed to its usual mean distance of 67.2 million miles. Not much of a difference, unless you have to walk it. Venus' orbital eccentricity is only 0.0067, so its aphelion distance is merely 0.6% greater than its average distance. (Venus' orbit is the least eccentric of all the planets.)
WEDNESDAY, MAY 21: MARS STATIONARY
Just a reminder: all the planets revolve around the Sun in the same direction. Though a planet's orbital speed varies as its distance from the Sun changes, none of the planets actually stop. So, when you see the phrase "Mars stationary," be aware that Mars hasn't halted. Instead, Mars appears to have stopped course against the stars and will then appear to change direction. Most of the time, planets move eastward relative to the background stars. At times, however, a planet will seem to become stationary before beginning a brief westward trek, called 'retrograde.' A superior planet -one farther from the Sun than Earth- goes into retrograde before and after opposition, as the faster moving Earth catches up with and then passes the planet. Mars has been in retrograde since March 1st: the last time it was stationary. Now, Mars resumes prograde motion.
WEDNESDAY, MAY 21: LAST QUARTER MOON
SUNDAY, MAY 25: MERCURY AT GREATEST EASTERN ELONGATION (22.7 DEGREES)
Neither Mercury nor Venus can ever be at opposition in our skies as they are inferior planets. (Closer to the Sun than Earth.) They'll therefore appear to oscillate from the western evening horizon to the eastern pre-dawn horizon. Tonight, Mercury is visible in the western evening sky. Remember, when an inferior planet is at greatest western elongation, it is visible in the eastern morning sky. When at greatest eastern elongation, it is visible in the western evening sky.
SUNDAY, MAY 25: MOON 2.2 DEGREES NNW OF VENUS
Whereas Mercury peeks up in the evening, Venus remains a pre-dawn eastern sky object. Tonight, one will find Venus and the crescent moon together against the brightening twilight. Observe them both a couple of hours before sunrise.
WEDNESDAY, MAY 28: NEW MOON
Beginning of lunation cycle 1131.
FRIDAY, MAY 30: MOON 5.9 DEGREES SOUTH OF MERCURY
A difficult sight, but not impossible. The thin, waxing crescent moon is close to Mercury in the western evening sky. If you want to challenge yourself, seek both the moon and Mercury tonight just as the twilight fades.
MERCURY: Mercury has been on a nearly month-long hiatus, having vanished in early April. Mercury emerges into the western evening sky by the second week of May. However, it will be a difficult object to find until the third week of May. VERDICT: Best to wait until after May 15 to find Mercury.
VENUS: This year, Venus reached its peak early and then started a long decline. Granted, even in decline, it outshines all the other planets. Venus remains a morning sky object. Venus attained its maximum brightness for 2014 on February 11; and reached its greatest western elongation on March 22. We'll observe Venus approaching the rising Sun throughout the spring and most of the summer. VERDICT: Remember that we'll lose Venus between late August and late December. (An entire autumn of absence.) Seek Venus while you can!
MARS: Alas, Mars retained the coveted pick planet diadem for merely one month. That was in April, when it was in opposition. Now, the fourth world remains quite bright, despite having attained its maximum brightness for the year in mid April. At May's beginning, it will be about as bright as Sirius, but by month's end, it will be noticeably dimmer. Mars will be the dominant evening planet in late evening, after Jupiter sets. (Saturn is up, but isn’t as bright.) VERDICT: Still a lovely evening sight! Seek the red eye in the sky throughout the night.
JUPITER: Jupiter was such a prominent sight throughout the autumn and into the winter. Now, it is approaching the Sun and setting earlier each night. Though it remains the brightest night sky sight apart from the Moon and Venus, Jupiter descends in the west. By July, it will vanish until August. VERDICT: It is bright, up early and now that it is moving away from the Winter Triangle (remember the Jupiter Diamond?) it will continue to adorn our sky throughout the spring. Catch it if you can.
SATURN: (PICK PLANET!!)
We honestly don't remember the last time we tossed the crown on the Lord of the Rings. This month, Saturn's the pick because it's at opposition. Granted, it is dimmer than all the planets at month's beginning, and only brighter than Mercury after mid month. VERDICT: A beautiful planet that will be up all night. How can you miss? (Note: Unlike Mars that will remain in the sky for the rest of 2014, Saturn will disappear for the month of November.)
PLANETS IN ORDER OF BRIGHTNESS ON MAY 1
VENUS - JUPITER - MARS - SATURN