April 2014 Night Sky Calendar
The cruelest month!
Or, so it's called, although we've never been able to figure out why anybody could so brutally disparage spring's first full month. April marks the transition period between the harsh winter cold and the harsh spring cold. Also, when April begins, we know we're merely 30 days shy of May, the true start of the warmer season.
One might also notice that winter's brilliant stars have moved low in the west while the splendid summer patterns ascend in the east. Between them, a comparatively dark section of sky; a dearth of bright stars, apart from Leo's Regulus, or Virgo's Spica.
If you've just joined us, we begin each month with a night sky calendar. We list the astronomical events we arrogantly deem noteworthy, although we neglect far more than we include. We conclude with a planet-watch section, noting the locations of the naked-eye planets. (i.e. not Uranus, Neptune or Pluto.)
THURSDAY, APRIL 3 MOON 6.8 DEGREES SOUTH OF THE PLEIADES
Of all the winter stars and patterns, the Pleiades will be the first to vanish with the setting sun, as it defines the winter star wall's western boundary. This evening, one will find it close to the waxing crescent moon. As the moon is only 17% illuminated tonight, it won't wholly obscure the Pleiades cluster. Admire the horned moon near the seven sisters this evening.
SUNDAY, APRIL 6 MOON 5.3 DEGREES SOUTH OF JUPITER
Though it will be close to quarter, the moon will certainly not wash away Jupiter. (Spoiler: we're going to rip the pick planet crown off Jupiter's bloated mug this month.) Observe both the moon and its giant planet companion in the early evening sky tonight!
MONDAY, APRIL 7 FIRST QUARTER MOON
TUESDAY, APRIL 8 MARS AT OPPOSITION (SILVER EVENT!!)
So, we'll ruin the surprise. Mars is this month's pick planet. After months in obscurity, Mars is finally coming into its own. Tonight, Mars rises around sunset and sets around sunrise because Earth passes directly between the red planet and the Sun. Consequently, Mars is at its most prominent. Mars will be up all night! The next Martian opposition occurs on May 22, 2016. The last opposition was on March 3, 2012. We would have awarded this event the gold medal, were it not for the lunar eclipse.
MONDAY, APRIL 14 MARS NEAREST EARTH (0.618 AU)
Now, wait a minute! Mars was at opposition on April 8th! Wouldn't it have been closest on that date? Not necessarily. If Earth and Mars traveled around perfectly circular orbits, then the opposition date would correspond precisely to that of closest approach. However, Earth and Mars travel around elliptical (oval) orbits. At the moment, Earth is moving away from the Sun each day. (Its distance from the Sun started increasing after its closest approach, perihelion, on January 4 and will continue to increase until reaching its greatest distance, aphelion, on July 4.) So, the distance separating Earth and Mars decreases after opposition this time. Today, they'll be 57 million miles apart. (In comparison, Mars' distance from Earth was 34.6 million miles during that August 2003 close approach.)
MONDAY, APRIL 14 MOON 3.4 DEGREES SOUTH OF MARS (BRONZE EVENT!)
See the nearly full moon within a hand's length of Mars tonight. We're designating this as the bronze event because Mars is so bright and it will remain close to the moon during tomorrow's total lunar eclipse. Though quite bright, the full and nearly-full moon will not wash out a planet, as the latter's light is so concentrated.
TUESDAY, APRIL 15 TOTAL LUNAR ECLIPSE (GOLD EVENT!!!) This morning, while the pious sleep, we'll behold a total lunar eclipse. During such eclipses, the full moon moves directly into Earth's shadow cone. Consequently, one will observe Earth's curved shadow migrate across the Moon's surface. When total, the Moon often exhibits a reddish hue, hence the term "blood moon."
The eclipse actually begins at 11:53 p.m. on April 14th. However, at this moment, Moon touches Earth's outer shadow, the penumbra. The resultant shading is so slight as to be unnoticable.
The umbral part of the eclipse begins at 1:58 a.m. We'll then see Earth's inner shadow, the umbra, start to move across the Moon. Totality, when the moon is completely within the shadow cone, begins at 3:07 a.m. Mid eclipse occurs at 3:47 a.m. Totality ends at 4:25 a.m. The Moon is completely out of Earth's inner shadow (umbra) at 5:33 a.m. The penumbral eclipse ends at 6:37 a.m. By this time, the Moon will have already set, but that makes little difference. We will be able to see all of the totality phase.
Quite interestingly, this lunar eclipse is the first of a tetrad, a series of four lunar eclipses occurring within the next two years (April 15, 2014; October 8, 2014; April 4, 2015; and September 28, 2015). We'll see most of the first two; precious little of the third, and all of the fourth.
Join us at the Southworth Planetarium on April 15th for total lunar eclipse viewing. We will cancel the event on the slight (97%) chance we'll have inclement weather.
THURSDAY, APRIL 17 MOON 1.2 DEGREES W OF SATURN
Mars gets the press this month, but May will be for Saturn. See the waning gibbous moon and the sixth world rising together in the early evening. Though they'll appear close together in our sky, observers in along southernmost South America and the South Pacific will be able to watch the moon move directly in front of Saturn. This direct passage of the moon in front of another body is called an "occultation.'
SATURDAY, APRIL 19 SUN ENTERS ARIES
The Sun leaves Pisces the Fish and enters Aries the Ram. Though the Sun occupies Pisces on spring's first day, the vernal equinox is still called the "First Point of Aries," as the Sun was once in Aries when spring started. Precessional wobbling causes the thirteen zodiac constellations to migrate around the entire ecliptic once every 26,000 years. Consequently, the vernal equinox point will eventually move through all thirteen ecliptic constellations. The Vernal Equinox point moved from Aries into Pisces in 68 BCE.* The ecliptic constellations are ARIES THE RAM, 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, and Pisces the Fish. The Sun will enter Taurus the Bull on May 14th.
SUNDAY, APRIL 20 EASTER DAY
The First Council of Nicea in 325 AD** established the date of Easter as the Sunday immediately following the first full moon after the Vernal Equinox. Consequently, the Easter date can vary from March 22 to April 25th. This year, Easter is almost as late as it can be.
(For the insatiably curious: 1818 was the last year in which we experienced the earliest possible Easter -March 22; the next March 22 Easter occurs in 2285; the next April 25th Easter happens in 2038.)
TUESDAY, APRIL 22 LAST QUARTER MOON
TUESDAY, APRIL 22 LYRID METEOR SHOWER PEAKS
We had so many splendid events this month that we ran out of medals by the time we came to the Lyrid meteor shower. The Lyrid shower certainly isn't the year's most spectacular: its maximum meteor emission rate is barely about 25. (This means that the shower produces a maximum of 25 meteors an hour under ideal observing conditions.) The best time to see a meteor shower is after midnight, when our part of Earth moves into the meteoroid stream. At this time, the last quarter moon will be rising: the interference will therefore be moderate, allowing one to easily observe the meteors.
We love this shower because its parent comet is C/1861 Gl Thatcher. It was last at perihelion in 1861 and isn't due to arrive at the next perihelion until 2280 or thereabouts. The Lyrid shower, so named as the meteors appear to emanate from the constellation Lyra, are pieces of a comet that is presently deep in the void, destined not to return for another 166 years. Fiery fragments of ghosts…
FRIDAY, APRIL 25 MOON 4.1 DEGREES NNW OF VENUS
After a fantastic month of spectacles, the moon offers an encore act with Venus, its most celebrated planetary companion. You'll see Venus and the moon well after midnight in the eastern sky.
SATURDAY, APRIL 26 MERCURY AT SUPERIOR CONJUNCTION
Finally, an 'academic event,' defined as one that is only interesting because it's interesting. There is nothing to see. Mercury moves behind the Sun and, of course, isn't visible.
TUESDAY, APRIL 29 NEW MOON (ANNULAR ECLIPSE: NOT VISIBLE HERE.)
A lunar eclipse is either preceded or followed by a solar eclipse. April 15th's lunar eclipse is followed by an annular eclipse visible only around Oceania. An annular eclipse is a solar eclipse which occurs when the moon doesn't entirely block the entire Sun during the occultation. Instead, it leaves a "ring of fire" around its periphery.
WEDNESDAY, APRIL 30 MOON 6.8 DEGREES S OF THE PLEIADES
Déjà vu? Yes, we've seen this event already: on April 3! The Moon draws close to the Seven Sisters (Pleiades) twice in April. However, notice the difference in position relative to the Sun. On April 3rd, the Moon and the Pleaides were 46 degrees from the Sun. Today, they'll be 19 degrees from the Sun. Earth moved significantly in its orbit during the intervening weeks. Soon, we'll lose the Pleaides to the Sun..at least for awhile.
MERCURY lurks low in the morning sky for the first half of April and then vanishes entirely into the solar glare. April 2014 is not a favorable month for the messenger planet. VERDICT: If you feel compelled to observe Mercury, venture out before sunrise the first week of April. After that, don't bother. Consolation: Mercury has a splendid apparition in May.
VENUS remains quite bright, of course, because it's always bright. However, like Mercury, Venus is a morning sky object. Unlike Mercury, though, Venus is observable all month. After attaining its greatest brilliance earlier this winter, Venus grows gradually dimmer. Of course, even when it is dimmest, Venus is 11 times brighter than Sirus, the night sky's brightest star. VERDICT: An easy sight for those who prefer early morning to early night. Remember, we'll lose Venus in late summer and it will not return to our sky until late December! (Imagine an autumn without Venus.)
MARS: (PICK PLANET!!) Yes, we know that Mars rarely wears the coveted diadem. However, this month, the war god world deserves the distinction. The fourth world is at opposition on April 8th and closest to Earth on April 14th. Though almost as bright as Sirius, Mars is still dimmer than Jupiter and much dimmer than Venus. VERDICT: Mars lovers have suffered frightful deprivations within the last year. Run outside this month at any time of night to behold the beautiful crimson planet!
JUPITER isn't weeping many bitter tears. It was the pick planet for so long, the strain of its fame was becoming a burden. Jupiter outshines Mars, but sets after midnight. By month's end, the giant planet will set at midnight. VERDICT: Still a treat for evening sky watchers, especially since it forms that beautiful diamond with the Winter Triangle Stars (Betelgeuse, Sirius and Procyon.) Of course, we'll lose the Winter Triangle soon, though eastward-trekking Jupiter remains visible unitl late June. (Unlike Venus, which takes an entire season off, Jupiter is only gone though July and very early August.)
SATURN is on the on-deck circle to obtain the diadem, just to mix our metaphors. Saturn is at opposition next month and will then be crowned the pick planet. This month, the sixth planet rises in the early evening and is visible for the rest of the night. Though dimmer than all the other naked eye planets, Saturn is still almost as bright as Arcturus and Vega. VERDICT: Not as red as Mars, or as bright as Venus, or as high as Jupiter at dusk, Saturn is still an easy sight throughout most of the night; find it if you must.
*We use BCE in place of BC, but have retained the AD. We're trying to make everyone mad at us.