Named meteor showers occur at roughly the same time each year. Astronomers estimate that the this year’s shower will be somewhat subdued because the Moon brightens the sky, which prevents the dimmer meteors from being seen. All of the meteors associated with the Lyrids shower will appear to come from inside the constellation Lyra. Even though the visible meteor trails are likely to begin outside of Lyra, and the end of the trails will be even farther away from Lyra in every direction, all of visible meteor trails associated with this shower can be traced backward to a common point within Lyra. The shower begins around April 16th and occurs every night through about April 25th. The shower will peak (highest number of meteors per hour) on April 22nd and 23rd. Lyra will rise in the east at about 11:30pm during this period, and can be found by locating its bright star Vega using a planisphere or smartphone app. To observe, be sure to dress warmly and sit in something comfortable, like a reclining lawn chair.
The full Moon occurs when the Moon is at the point in its orbit on the side of the Earth opposite the Sun. Another way of describing this, is to say that the Earth is directly between the Sun and Moon when the Moon is full (fully lit). The Earth, like all objects upon which sunlight falls, the casts a shadow. This shadow extends into space in the Moon’s direction at full Moon. The Moon usually misses the Earth’s shadow by passing just a little above or below it at full Moon. But the Moon will pass through the Earth’s shadow this month in the early morning hours of April 15th. The Moon enters the penumbra (the lightest part of the Earth’s shadow) at 12:37am EDT, but the best viewing begins at about 2am when the Moon enters the umbra (the darkest part of the Earth’s shadow). Totality occurs when the Moon is completely inside the umbra from 3:06am until 4:27am, at which time it begins to re-enter the penumbra. This stage of the eclipse is the beginning of the Moon’s exit from the Earth’s shadow. The Moon completely exits the umbra at 5:30am, and the eclipse is completely over when the Moon exits the encumbrance at 6:30am.
There are two really neat things to note about the eclipse. First, the “sunset” effect. The portion of the Moon within the umbra will have a distinct reddish cast as a result of the Sun’s rays passing through the edges of the Earth’s atmosphere. As the eclipse progresses, the umbra can first be seen on the eastern edge of the Moon. Over the next hour or so, the portion of the Moon covered by the umbra will grow larger, until the Moon is completely engulfed by the umbra. The reverse will occur as the Moon slides back out of the umbra. Here’s the other neat thing to note. What the observer is actually watching as the Moon passes through the Earth’s shadow is the Moon moving along it’s orbital path around the Earth.
Events come and go, but are interesting to observe. Event durations can vary from an instant to seconds, minutes or days, or even longer. Examples include eclipses, certain planetary arrangements and alignments, meteor showers, and transits of the Sun. One must know when, where, and how to observe an event in the night sky. Most events covered in Jim Johnson’s Astronomy provide insight into how the Solar System actually works.
While Deep Space Objects (DSOs) technically includes stars, it is generally about nebulae, galaxies, and star clusters. Most are small and dim, so a telescope is needed to see them. Others can be seen with modest magnification of binoculars or a small telescope. Initially I will limit this newsletter to those visible with the unaided eye, and eventually cover those that can be seen with some magnification. It is important to note that DSOs never appear as bright and colorful to the eye, even when using a amateur telescope, as they do in astrophotographs. This is because camera film (in days past) or sensors can gather light over much longer periods of time than can the human eye. Many of the brighter and more interesting DSOs were cataloged by Charles Messier in the 18th century. Messier objects are assigned an ‘M’ number.
To the casual observer, the planets are indistinguishable from bright stars. For the purposes of our unaided eye observation, the stars remain fixed in place relative to one another. Even without magnification, planets can be observed to move among the stars as they move along their orbital paths around the Sun. Movement of the planets closer to the Sun, which orbit the Sun faster than the planets that are farther from the Sun, can be detected from one night to the next. The motions of the planets more distant from the Sun can be detected over the course of weeks or months. I have actually seen Venus’ movement over the span of a few minutes through a telescope during the 2012 transit of Venus across the face of the Sun. Even when greatly magnified, stars will never appear as more than a single point of light when observed from Earth. Planets on the other hand, will appear larger with magnification, and a disk can be observed. Features on some of these disks can be observed with sufficient magnification.
Gemini, the twins, is a zodiacal constellation that was also one of the 48 constellations cataloged by 2nd century astronomer Ptolemy that remain among the 88 modern constellations. This constellation located above Orion’s left shoulder, and between Taurus and Cancer on the ecliptic. It is highest in the sky at nightfall in March, and is quickly identified by two rather bright stars of approximately equal brightness, Castor and Pollux, that represent each of the Gemini twins. The ecliptic reaches its northernmost separation from the celestial equator in Gemini, and the Sun’s arrival at this point marks the Summer Solstice. The annual Geminids is a prominent annual meteor shower that peaks between December 13th and 14th. Only one Messier object, M35, is located in Gemini.
© James R. Johnson, 2014.
Taurus, one of the zodiacal constellations, is most easily identified by it’s distinct and bright V-shaped asterism that represents the face of the bull. Taurus was one of the 48 constellations cataloged by the 2nd century astronomer Ptolemy that remains among the 88 modern constellations. This constellation reaches its highest nightfall ascension in February, and is found by tracing Orion’s belt stars to the right to Aldebaran (Alpha Tauri), the bright reddish star nearby. The outlying stars in this constellation can be difficult to locate in light polluted skies.
With the exception of the brightest star, Aldebaran, the V-shaped asterism previously mentioned are stars withing the Hyades open star cluster, which is the closest open star cluster to us here on Earth. Many more stars in this cluster can be detected with binoculars or a small telescope. Also in Taurus is the brightest an most distinct open star cluster that we can see from Earth, The Pleiades (M45, or The Seven Sisters), which is located northwest of the V-shaped astersm toward and near Perseus. This open star cluster, sometimes mistakenly thought to be the Little Dipper, becomes even more beautiful with even the slightest magnification. The only other Messier object is M1, the Crab Nebula, which was created by a supernova explosion that was bright enough to be seen in the daytime sky in July of 1054.
© James R. Johnson, 2014.