Celestial Highlights for April 2014
Posted: Tuesday, April 1st, 2014
by Robert Victor and Robert D. Miller
Mars at its closest and brightest, a total lunar eclipse, two asteroids within easy reach of binoculars, and a whole slew of bright stars preparing for their annual departure from the western early evening sky.
April 2014 at dusk
Jupiter at mag. –2.2 to –2.0 is clearly the brightest evening “star”. Mars, varying from mag. –1.4 to –1.5 to –1.2 in April, briefly equals or slightly outshines Sirius (–1.4) as the red planet passes opposition and closest approach to Earth in the second week. Next in apparent brightness, in a virtual 3-way tie: Arcturus (–0.05) and Capella (+0.08), are high in the sky and well seen, but Vega (+0.03), just rising at month’s end from northern California, is much dimmed by our atmosphere, as is Saturn, also just rising around mid-twilight at month’s end
Going, going, … Jupiter, Betelgeuse, and the surrounding stars of the Winter Hexagon are in various stages of descent into the western sky. Beginning by mid-April, students can use the observing log to keep daily records of their sightings of bright stars and planets during evening twilight, as well as any sounds of nature they hear during the observing sessions.
In the eastern half of the sky, Regulus, Arcturus, and (barely) Mars are already up and ascending on April 1. Mars is at opposition to the Sun and visible all night on April 8, followed by Spica just 5 days later.
The Moon forms striking gatherings with stars and planets during the first half of April. (If you spotted the 32-hour young crescent Moon low in the west at dusk on March 31, congratulations!) The waxing crescent with earthshine on its dark side will be a beautiful sight for the first several evenings of April as it climbs higher each night.
On Thursday evening, April 3, the Moon will appear closely lower right of Aldebaran, eye of Taurus, and among the stars along the right side of the “V” of the Hyades star cluster forming the Bull’s face. Sometime between 8:00 p.m. PDT (in NW corner of California) and 8:20 p.m. (in SE corner of our state), the leading dark edge of the Moon will occult, or cover the 4th-mag. star Delta-3 Tauri, causing the star to suddenly “wink” out. The occultation will be best seen in binoculars or a telescope. The event takes place in twilight, only 15 minutes after sunset in the NW corner of California and likely too difficult to observe, improving to near the end of twilight in the SE corner of the state. Sample times of the star’s disappearance: 8:06 p.m. in San Francisco and Sacramento, 8:15 p.m. in Los Angeles, and 8:17 p.m. in San Diego and Palm Springs. Just over an hour later (about 9:25 p.m. in Palm Springs), the star reappears, but at the bright edge of the Moon, where it will not be as easy to observe the exact moment of emersion.
On Sunday evening, Apr. 6, the Moon, nearing First Quarter phase (half full and 90° east of the Sun), passes 5° S of Jupiter. On the next evening, the Moon is widely S of Pollux, one of the Gemini Twins, and on Thurs. Apr. 10 it passes widely S of Regulus, heart of Leo, the Lion.
During all those evenings, the waxing Moon has been tracking south of the ecliptic, or “below” Earth’s orbital plane. But that will come to an end late on the night of April 14, as the Full Moon returns close enough to the ecliptic plane to be completely immersed in the umbra, or dark central core of Earth shadow – causing a total lunar eclipse!
The eclipse begins as the Moon begins to enter the Earth’s umbra, or dark central core of Earth’s shadow, late on Monday evening, April 14, at 10:58 p.m. PDT. Not long after the partial eclipse gets underway, the circular shape of the edge of Earth’s shadow will become evident.
The Earth’s diameter is nearly 3.7 times the Moon’s, but the Earth’s shadow, during this eclipse, will appear only 2.7 times as large as the lunar disk. That’s still large enough for the Moon to easily fit within it, with plenty of room to spare!
As more of the Moon is immersed in Earth’s shadow, the reddish color of the shadow becomes noticeable. The reddish illumination is sunlight which has passed through the Earth’s atmosphere and gotten refracted, or bent, into the Earth’s shadow. When light passes through Earth’s atmosphere, most of the bluer light (of shorter wavelengths) gets scattered by molecules in the air, and most of the red light gets through.
Total eclipse begins at 12:07 a.m. early Tuesday morning, April 15, as the Moon first becomes completely immersed in the umbra. Even so, the Moon may have a bright edge to it (the WSW limb, closest to Spica), because the shadow’s outer edge is usually much brighter than the center, which receives only sunlight which has passed deep within Earth’s atmosphere on its way to the Moon.
The brightness and color of the Moon during a total eclipse varies widely from one eclipse to another, depending on atmospheric conditions over places on Earth where Sun is rising or setting at time of eclipse. Sunlight must pass through these zones in order to reach Moon during total eclipse, and presence of clouds in lower atmosphere or volcanic aerosols in stratosphere can block much of the sunlight and darken Earth’s shadow. The great volcanic eruptions of 1963, 1982, and 1991 were each followed by exceptionally dark total lunar eclipses. The French astronomer Andre Danjon devised a five-point brightness or luminosity scale to help observers rate darkness and color of a total lunar eclipse. Observe for yourself how the eclipse on night of April 14-15 compares to others! Get Danjon’s scale and then select the rating from the 5-point L (luminosity) scale best matching the darkness and color of the Moon at beginning, middle, and end of totality.
The 78 minutes of total eclipse is also a perfect time for using binoculars to locate the asteroids Vesta (mag. 5.7) and Ceres (mag. 7.0), at peak brightness and just 2.4° apart in Virgo, an easy star-hop from the dimmed Moon and Spica. These asteroids are the destinations of the Dawn space mission; Dawn has already visited Vesta and is on its way to Ceres, arriving there in 2015. See the very simplified Ceres-Vesta finder chart in this article for use just during the eclipse.
Deepest eclipse occurs at 12:46 a.m. PDT, when the northern edge of the Moon comes closest to the center of Earth’s shadow.
Total eclipse ends at 1:25 a.m., when the Moon’s SE limb begins to come out of Earth’s shadow.
The Moon’s withdrawal from the umbra is complete, and the concluding partial eclipse is over, at 2:33 a.m. PDT.
For perhaps half an hour before 10:58 p.m. and after 2:33 a.m., a light dusky shading – the penumbra, or region of partial shadow – may be noticed on a portion of the Moon’s disk.
April 2014 at dawn
Venus (mag. –4.4 to –4.1) continues to dominate the morning sky. Find it in the ESE in morning mid-twilight, drifting farther north as month progresses. A telescope shows Venus in gibbous phase, fattening from 54 to 66 percent full, while the disk shrinks from 22 to 17 arcseconds across. Saturn is a steady yellow “star” of mag. +0.3 to +0.1 sinking slowly in SW. Telescopes reveal the rings tipped 22° from edgewise. To Saturn’s lower right are bright reddish Mars and blue-white first-magnitude Spica, but they drop below the W to WSW horizon before month’s end, after passing opposition on April 8 and 13, respectively.
Other bright objects in the morning sky are golden Arcturus, well up in W to upper right of Mars and Spica; reddish Antares, heart of Scorpius, in SSW to SW; and the Summer Triangle of Vega, Altair, and Deneb high in the east, topped by its brightest member, Vega, approaching overhead.
April’s waning Moon, just hours after the lunar eclipse, is still close to Spica and Mars at dawn on the 15th. Early on the morning of the 17th, the Moon passes closely south of Saturn, and on the next morning, Apr. 18, the gibbous Moon passes widely north of Antares. The Last Quarter (half full) Moon on the morning of Apr. 22 will be 5° north of the ecliptic, near stars marking the head of Capricornus, the Sea-goat. On the mornings of April 25 and 26, the crescent Moon will appear near Venus. One week after Last Quarter, at the New Moon of Apr. 29, our satellite will pass through the descending node of its orbit and cause a solar eclipse, annular in a small part of Antarctica, and partial in Australia and the south Indian Ocean.
Moon returns to evening sky. At dusk on April 30, the young 1.9-day-old crescent Moon appears low in WNW to the lower right of Aldebaran. In the 27 days since April 3, the Moon has completed nearly one circuit around the zodiac, and a very eventful trip at that! (The Moon’s sidereal, or star-to-same-star, period is 27.3 days.)
Future events: In May, four bright planets adorn the sky at dusk, and Venus will have a very close conjunction with the Moon at dawn, the best one during Venus’ current morning apparition. There’s a good chance for a really strong but brief meteor outburst (a storm?) on the night of May 23-24. All these events will be illustrated or described in the May 2014 issue of the Abrams Planetarium Sky Calendar,
This month’s lunar eclipse is the first of a tetrad, four consecutive total lunar eclipses at six-month intervals. And all are visible from California! For this one, the 78-minute totality began at 12:07 a.m. on Tues. April 15. The next will occur on Wed. Oct. 8, with a 59-minute totality getting underway at 3:25 a.m.
Then in 2015, on Sat. April 4, a very brief 5-minute totality will commence at 4:58 a.m. And, finally, later that year, on Sunday, Sept. 27, a 72-minute totality will get underway at the very family-friendly time of 7:11 p.m.
This year’s opposition of Mars on April 8, with close approach 57 million miles from Earth on April 14, will be improved upon in coming years. In late May 2016 Mars will approach within 47 million miles of Earth, and in late July 2018, it will come even closer, within 36 million miles. But at both those apparitions Mars will appear much lower in the sky where seeing is usually poor, so take advantage of this spring’s opportunity for close-up views of Mars through a telescope. For helpful tips, click here.
Robert D. Miller, who provided the twilight charts, did graduate work in Planetarium Science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.
Posted: Wednesday, October 12th, 2016
by Jessica Sawko
In June 2016 California submitted a waiver application to discontinue using the old CST (based on 1998 standards) and conduct two years of pilot and field tests (in spring 2017 and 2018, respectively) of the new science assessment designed to support our state’s current science standards (California Next Generation Science Standards (CA-NGSS) adopted in 2013). The waiver was requested because no student scores will be provided as a part of the pilot and field tests. The CDE received a response from the U.S. Department of Education (ED) on September 30, 2016, which provides the CDE the opportunity to resubmit a revised waiver request within 60 days. The CDE will be revising the waiver request and resubmitting as ED suggested.
At its October 2016 North/South Assessment meetings CDE confirmed that there will be no administration of the old CST in the spring of 2017. (An archive of the meeting is available at http://www.cde.ca.gov/ta/tg/ai/infomeeting.asp.) Learn More…
Posted: Thursday, September 22nd, 2016
by Carol Peterson
1) To celebrate the 100th anniversary of the National Park Service, Google has put together a collection of virtual tours combining 360-degree video, panoramic photos and expert narration. It’s called “The Hidden Worlds of the National Parks” and is accessible right from the browser. You can choose from one of five different locales, including the Kenai Fjords in Alaska and Bryce Canyon in Utah, and get a guided “tour” from a local park ranger. Each one has a few virtual vistas to explore, with documentary-style voiceovers and extra media hidden behind clickable thumbnails. Ideas are included for use in classrooms. https://www.engadget.com/2016/08/25/google-offers-360-degree-tours-of-us-national-parks/. Learn More…
Posted: Thursday, September 22nd, 2016
CSTA is pleased to announce the winners of the 2016 CSTA Awards for Distinguished Contributions, Margaret Nicholson Distinguished Service Award, 2014 and 2015 PAEMST-Science recipients from California, and the 2016 California PAEMST Finalists. The following individuals and organizations will be honored during the 2016 California Science Education Conference on October 21- 23 in Palm Springs. This year’s group of awardees are truly outstanding. Please join us in congratulating them!
Margaret Nicholson Distinguished Service Award
The Margaret Nicholson Distinguished Service Award honors an individual who has made a significant contribution to science education in the state and who, through years of leadership and service, has truly made a positive impact on the quality of science teaching. This year’s recipient is John Keller, Ph.D. Dr. Keller is Associate Professor, Cal Poly San Luis Obispo and Co-Director, Center for Engineering, Science, and Mathematics Education, Cal Poly San Luis Obispo. In her letter of recommendation, SDSU science education faculty and former CSTA board member Donna Ross wrote: “He brings people together who share the desire to make a difference in the development and implementation of programs for science teaching. Examples of these projects include the Math and Science Teaching Initiative (MSTI), Noyce Scholars Program, Western Regional Noyce Initiative, and the Science Teacher and Researcher (STAR) program.” Through his work, he has had a dramatic impact on science teacher education, both preservice and in-service, in California, the region, and the country. He developed and implemented the STEM Teacher and Researcher Program which aims to produce excellent K-12 STEM teachers by providing aspiring teachers with opportunities to do authentic research while helping them translate their research experience into classroom practice. SFSU faculty member Larry Horvath said it best in his letter:“John Keller exemplifies the best aspects of a scientist, science educator, and mentor. His contributions to science education in the state of California are varied, significant, and I am sure will continue well into the future.” Learn More…
Posted: Tuesday, September 20th, 2016
by Peter A’hearn
NGSS is a big shift. Teachers need to learn new content, figure out how this whole engineering thing relates to science, and develop new unit and lesson plans. How could NGSS possibly make life easier?
The idea that NGSS could make our lives easier came to me during the California State NGSS Rollout #1 Classroom Example lesson on chromatography. I have since done this lesson with high school chemistry students and it made me think back to having my own students do chromatography. I spent lots of time preparing to make sure the experiment went well and achieved the “correct” result. I pre-prepared the solutions and organized and prepped the materials. I re-wrote and re-wrote again the procedure so there was no way a kid could get it wrong. I spent 20 minutes before the lab modeling all of the steps in class, so there was no way to do it wrong. Except that it turns out there were many. Learn More…
Posted: Tuesday, September 20th, 2016
by Robert C. Victor. Twilight sky maps by Robert D. Miller. Graph of evening planet setting times by Dr. Jeffrey L. Hunt
Our evening twilight chart for September, depicting the sky about 40 minutes after sunset from SoCal, shows brilliant Venus remaining low, creeping from W to WSW and gaining a little altitude as the month progresses. Its close encounter within 2.5° N of Spica on Sept. 18 is best seen with binoculars to catch the star low in bright twilight. The brightest stars in the evening sky are golden Arcturus descending in the west, and blue-white Vega passing just north of overhead. Look for Altair and Deneb completing the Summer Triangle with Vega. The triangle of Mars-Saturn-Antares expands as Mars seems to hold nearly stationary in SSW as the month progresses, while Saturn and Antares slink off to the SW. Learn More…