Notice the number of instances this quarter when an event takes place on a certain date in the Pacific Time Zone, but on the following date in the Eastern Time Zone? That’s because those events, such as the Full Moon in May, occur just before midnight, PDT, and correcting for EDT advances the clock by three hours, crossing midnight and—because we start our days at midnight—changing the date.
April 12, 1961 is the day that Russian cosmonaut Yuri Gagarin became the first human to fly in space, orbiting Earth three times aboard his Vostok spacecraft. The date has since become an international commemoration known as “Yuri’s Night,” marked by talks, demonstrations of technology, and presentations of art and music that embrace the spirit of space exploration.
Visible on Spring evenings are the stars of the Zodiacal constellation Leo the Lion, formed by a “sickle,” or backward question-mark, followed by a small right triangle just east of it. The brightest star in Leo is Regulus, the “dot” of the backward question-mark, which represents the Lion’s heart. The third-brightest in the constellation is Denebola, at the sharpest point of the triangle representing the Lion’s hindquarters, and itself said to represent the tip of the Lion’s tail. The second-brightest star in Leo is at the back of the Lion’s neck, in the backward question-mark that forms his head and heart. This star, known as Gamma Leonis, has the traditional Arabic name Algieba, and is about 130 light years away. Telescopes reveal that it is actually a close binary system, consisting of two stars, and the brighter component is known to be orbited by a planet approximately 2.14 times the mass of Jupiter. Meanwhile, the brightest star in the night sky known to have a planet is also visible—look low in the west just after sunset for Pollux, the brighter of the two stars marking the heads of Gemini the Twins (fainter sibling Castor is to the right of Pollux). The Moon passes between Pollux and Procyon (in adjacent Canis Minor) on April 17. It passes distantly in line with Castor and Pollux on the evenings of May 15 and June 11, and brilliant Venus lines up, forming an interesting progression with medium-bright Castor and bright Pollux very low in the west-northwest on the evening of June 24.
During April—particularly when Mars passes behind the Sun on April 17—NASA’s Mars Science Laboratory (also known as the Curiosity rover) is out of contact with Earth and on its own. No communications will be attempted with the robotic field laboratory on the surface of the Red Planet out of concern that solar interference could corrupt any of the commands, but Curiosity will still be in contact with two spacecraft that are in orbit around Mars. It will also perform preprogrammed work in situ, such as monitoring environmental conditions and radiation, which don’t require much human intervention. Science operations, including, rock and soil analysis, photography, and roving, will resume when the angular separation between Mars and the Sun widens, allowing for direct contact with Earth in May.
Astronomy Day, founded in Northern California in1973, is celebrated on a Saturday nearest the first quarter Moon in either April or May. It’s part of a broader event, Astronomy Week, which begins the preceding Monday. This year, Astronomy Day falls on April 20, and observatories, planetariums, science museums, and amateur astronomy clubs nationwide will be bringing the science of stargazing to the people with activities, presentations, or other special events. Check with your nearest astronomy organization or science center to find out how they’ll be celebrating!
Asteroids making their closest approach to Earth during April (though none so close as to be of any concern whatsoever, all being more than the distance from Earth to the Sun): 91007 Ianfleming (007...get it?), 10189 Normanrockwell (artist), 3264 Bounty (of “Mutiny” fame), 5231 Verne (author Jules), 9500 Camelot (of Arthurian legend), 79896 Billlhaley (early rock & roller whose name is often misused as that of the more famous Halley’s Comet), 3153 Lincoln (U.S. President), 16626 Thumper (after the character in the 1942 Disney cartoon “Bambi”), and 7016 Conandoyle (Sir Arthur, creator of Sherlock Holmes)
On May 5, 1961, Alan Shepard became the first American to fly in space, although unlike Yuri Gagarin’s 1-orbit/nearly 2-hour flight, Shepard’s trip lasted only 15 minutes, basically going up and coming down, splashing into the Atlantic only 302 miles away from his launch site at Cape Canasveral.
An eclipse season occurs this quarter, when eclipses of the Sun and Moon are possible. This happens because the Moon’s orbit around Earth is tilted by 5.5 degrees, and most of the time, the Moon misses the perfect alignment with Earth and the Sun that can cause an eclipse. It’s only when the Moon’s orbit intersects the plane of Earth’s orbit around the Sun that this can happen, and this only occurs about every six months. Unfortunately, the two lunar eclipses that are occurring this eclipse season are quite unremarkable and barely visible: during the first (on April 25), the Full Moon passes mostly through only the very diffuse outer shadow of our planet (the penumbra), and in the second (on May 25), it barely grazes the penumbra, rendering these eclipses virtually undetectable. On the other hand, the solar eclipse that occurs this season (on May 10) is an annular eclipse whose path crosses the Pacific Ocean. Observers in Hawaii will see a partial eclipse of the Sun during which about half the Sun’s diameter will be blocked by the silhouette of the Moon. There can be two eclipse seasons per year, roughly six month apart, and in a single year, there can be seven eclipses of some kind of either the Sun or the Moon.
Asteroids having their nearest approach to Earth in May, though none closer than Earth’s distance to the Sun: 3623 (vaudevillian Charlie) Chaplin, 5020 (science fiction author Isaac) Asimov, 9007 (fictional superspy 007) James Bond...and, in an interesting coincidence, 13070 (actor) Seanconnery, 5102 (inventor/statesman) Benfranklin, and 16809 (island) Galapagos, 15131 (actor) Alanalda, 334 (city of) Chicago, 5277 (city of Brisbane), and 6349 (city of) Acapulco. In June, 19383 (rock band) Rolling Stones, 5049 (fictional detective Holmes) Sherlock, 5405 (“Peter Pan” home) Neverland, 1772 (cosmonaut Yuri) Gagarin, 13677 (deep-sea submersible) Alvin, 1640 (fictional Captain) Nemo, 25924 (author/humorist) Douglasadams, 42776 (city of) Casablanca, 4147 (Beatle John) Lennon, 4148 (Beatle Paul) McCartney, and 3834 (rocker Frank Zappa) Zappafrank. There are others, of course, but these are the ones with the most fun names from pop culture. Many more asteroids are named after figures from science, history, and mythology.
A rare opportunity to spot the distant planet Uranus presents itself on the morning of June 30, when the waning crescent Moon is located just 3.5 degrees north of the faint, green planet, both against the stars of the constellation Pisces the Fishes. Theoretically within naked-eye visibility, Uranus is very slow-moving and easily mistaken for a star. In fact, records indicate that it was observed as early as 1690, but its non-stellar nature wasn’t determined until observed by Sir William Herschel in 1781, and even he thought he was looking at a comet. It wasn’t until 1783 that Herschel himself publicly agreed that he had discovered a planet—in one fell swoop doubling the diameter of the known solar system. Through binoculars or telescope, Uranus appears as a conspicuous, greenish “star” in a region fairly devoid of bright objects.
Also, on June 30, 1908, an asteroid estimated to have been roughly half the size of a football field entered Earth’s atmosphere and exploded over Tunguska, a (fortunately) remote region in Siberia, releasing 1000 times the energy of the atomic device dropped on Hiroshima during World War II and flattening a forest of 80 million trees, with the heat-blast being felt over 40 miles away, where a man was knocked to the ground, and atmospheric effects due to dust from the explosion detected over the U.S. for several months afterward. By comparison, 2012 DA14, the asteroid which passed 17,200 miles from Earth on February 15, 2013, is estimated to have been about the same size as the Tunguska object.