Image of Sputnik 1 from Air and Space Museum

Notes for the Season features information on meteor showers, space exploration events, and astronomy-related anniversaries from April through June 2017.

Sunrise/Sunset

                             Sunrise              Solar Noon           Sunset

April 1             6:55 am PDT         1:13 pm PDT       7:33 pm PDT

May 1              6:14 am PDT         1:06 pm PDT       8:01 pm PDT

June 1              5:49 am PDT         1:07 am PDT       8:26 pm PDT

(Times are for San Francisco, CA, and will vary slightly for other locations.)

Notes for Spring
Comet 41P/Tuttle-Giacobini-Kresak, photo credit: Astronomy Now

On April 1, Comet 41P/Tuttle-Giacobini-Kresak is closest to Earth, at a distance of 13 million miles (21 million kilometers)–its closest approach in a century, and perhaps visible in binoculars as it passes along the body of Draco the Dragon through April 20. This region of the sky is above the horizon all night, but highest at about 2-3 am. After the 20th, the comet sneaks between Hercules the Strongman and Lyra the Harp, slowly fading as it moves southward into Ophiuchus the Serpent-Bearer. Typical of comets, 41P looks like a diffuse spot of light in binoculars and small telescopes, and long photographic exposures have revealed a greenish color.

Yuri Gagarin Night Logo, Fair use, https://en.wikipedia.org/w/index.php?curid=45094304

On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human in space, orbiting the planet once inside his Vostok capsule in a flight that lasted 108 minutes from launch to his safe return within Soviet borders. Ejecting from the spherical descent module at 23,000 feet (7 kilometers, or 4.3 miles), Gagarin parachuted separately to the ground, and by his own account asked a startled farmer where he could find a telephone. Since 1981, the 20th anniversary of Gagarin's pioneering flight, this date has been marked by worldwide celebrations of spaceflight known as "Yuri's Night."

Lyrid meteor shower

April 22-23 is the peak of the Lyrid meteor shower, one of the oldest displays known, with observations dating back 2,600 years. Active from April 19 through the 24th, this display usually produces about a dozen swift meteors per hour under ideal conditions, caused by dust particles from Comet Thatcher burning up as they enter the atmosphere at high speed. The shower's name comes from how the meteors appear to radiate from the vicinity of the constellation Lyra the Harp, which rises around 10 pm. Fortunately, at the shower's peak, the Moon will be a waning crescent that rises shortly before dawn, and its light shouldn't interfere. While the Lyrids are normally a modest display, unexplained outbursts of more than 100 per hour were observed in 1922, 1945, and 1982.

Cats celebrating International Astronomy Day

April 29 is International Astronomy Day. Founded in 1973, this day is celebrated on a Saturday in April or May nearest the first quarter Moon and is an opportunity for amateur and professional astronomers to share their enthusiasm for stargazing at museums, planetariums, observatories, and community centers around the country. Weather permitting, there are also "star parties" taking place this evening. Contact your local science center or amateur astronomy club for more information.

Photo "The Witness," copyright 2013 by Jason Jenkins, CC BY-SA 2.0

The Eta Aquarid meteor shower is active May 1-12 and peaks May 5-6. This is one of two showers caused by Earth's passage through the dust trail of Halley's Comet (the other is the Orionid shower in October). The Eta Aquarids usually produce about 20 meteors per hour for observers located at dark sites and when there's no bright Moon in the sky. Unfortunately, the point in the sky from which the meteors seem to radiate is located in the southern part of the sky and doesn't rise until about 3 am, definitely making this shower a better display just before dawn on the 6th. By that time, the waxing gibbous Moon (approaching full) will be low in the west, so moonlight shouldn't interfere too much with observations.

Photo "Summer Solstice Sunrise Over Stonehenge," copyright 2005 Andrew Dunn, CC BY-SA 2.0

June 20 is the summer solstice in the northern hemisphere, although the moment the Sun reaches its farthest northern separation from the celestial equator is at 9:25 pm, while the Sun is below the horizon. On the days before and after, sunrise and sunset are at their northernmost, and the arc of the Sun is highest for the year, making for a long daylight period. By common usage, this is usually considered the first day of summer, although from this day on, the length of the daylight period gradually grows shorter. Due to the large bodies of water on our planet that absorb and retain heat differently from land, a seasonal lag occurs, delaying the onset of the warmest weather until a month or two after the solstice. For the southern hemisphere, this is the winter solstice.

Flattened trees after the Tunguska Event of 1908

June 30 is the anniversary of the Tunguska Event of 1908, when a mysterious and powerful explosion occurred in the Tunguska region of Siberia. Scientists suspect that a comet or asteroid exploded in the atmosphere, flattening a 2,000 square-kilometer (770 square-mile) forest and toppling approximately 80 million trees. Reportedly, the shock wave knocked a man down 40 miles away. This is also observed as Asteroid Day, founded in 2015 and now officially recognized by the United Nations as an International Day, to promote awareness of asteroids and the potential hazards they pose to our planet.

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2017 Pocket Almanac

2017 Pocket Almanac

Download the Morrison Planetarium's 2017 Pocket Almanac to stay up-to-date on eclipses, meteor showers, satellite spottings, and more.

2017 Morrison Planetarium pocket almanac