10 results for author: Larry Stookey

Capella: four stars that appear to be one

As I mentioned in the February 1st issue article about the constellation Auriga the Charioteer, the name Capella means “female goat” or “little female goat” in Latin. Like many objects visible to us in the night sky, Capella is not just a single star. It consists of two binary pairs. A binary pair is two stars revolving around a common center, somewhat like two ice skaters holding hands while they spin.

Look for Auriga on February 21

In the deep midwinter, gaze overhead in the middle latitudes of the Northern Hemisphere in the late evening and you will see the constellation we call Auriga the Charioteer. The six brightest stars can form either an irregular hexagon, or an irregular pentagon with one outlier star. The brightest, Capella, lies to the northeast. Capella is actually a combination of two binary systems. What we see as one star is a close association of one of these binaries, two bright yellow stars that revolve around a common center. These are only about 43 light-years away from Earth. Their proximity plus their size and temperature, gives the visible “Capella” a ...

OBJECTS IN THE SKY: CONJUNCTIONS – JUPITER AND SATURN

  Looking low in the southwest sky at dusk this December, two bright objects stand out. The lower and brighter one is the planet Jupiter. Higher and a bit to the left is Saturn. During this past spring and summer, the apparent distance between the planets has been decreasing. On December 21, 2020, the two planets will be at their minimum separation, about 0.15° apart. This is only about one-third the width of the full moon. Jupiter and Saturn have not been this close since the year 1226 A.D. In historical perspective, Francis of Assisi died in that year and Genghis Khan ruled the Mongol Empire.   A conjunction occurs when two ...

OBJECTS IN THE SKY

  "Between 1914 and 1916, Gustav Holst composed his orchestral suite “The Planets”. He had been introduced to astrology by Clifford Bax while on holiday in Majorca in 1913 and held astrology to be his “pet vice”. His work “The Planets” represented the seven known planets of the time. These were Mercury, Venus, Mars, Jupiter, Saturn, Neptune and Uranus. Earth, which had no astrological significance, was excluded, as was Pluto, which had not yet been discovered. The sixth movement of “The Planets” was “Saturn”, subtitled “The Bringer of Old Age”. In the Roman pantheon, Saturn not only brought old age among humankind, ...

THE CELESTIAL CRUSTACEAN

  One of the official duties of the Chinese emperor around the end of the first millennium was to explain to his people any unusual occurrences in the heavens. To this end, he employed astronomers to observe the sky. In 1054 A.D., these astronomers reported to Emperor Renzong (1010 – 1063 A.D.) the appearance of a “guest star” in the constellation we call Taurus the Bull. “Guest star” was their term for any bright object that suddenly appeared in the sky and then disappeared after a relatively short time. This “guest star” was a supernova, which is a star that has used up its nuclear fuel, collapses inward, and then explodes. The ...

OBJECT IN THE SKY

  "The International Space Station (ISS) made at least two visible passes over Wisconsin (taking sky cover into consideration) at around 9:00 PM (0200 GMT or Zulu) during the latter part of March and early April. It is difficult to mistake the ISS for any other object in the sky. Often passing high in the sky, it appears brighter (magnitude between –2.0 and –3.6 during these passes) and faster than an aircraft but much steadier and slower than a meteor. Depending on the time and the season, it fades as it enters Earth’s shadow and disappears from sight. As the ISS ascends this month, it passes Venus, which is currently almost due west ...

PRECESSION AND THE NORTH STAR

  "A child's top spins. It not only spins, it wobbles. After a short time, the handle of the top begins moving in a circle. This happens because of the uneven distribution of the weight (or mass) of the child's top. A slight "nudge" allows the wobble, called precession. Our planet Earth acts like a child's top. The movement of celestial bodies was very important to the ancient Egyptians. Much of interior Egypt had been a desert for a very long time. The production of food was dependent on the flooding of the Nile, which laid down a layer of fertile sediment suitable for planting. This flooding was very regular and could be predicted using a ...

OBJECTS IN THE SKY – PERSEUS AND ALGOL

The star Algol appears in the constellation Perseus. Stars in constellations generally have technical names with Greek-letter prefixes (alpha, beta, gamma, etc.) in decreasing order of brightness, or magnitude. Thus Algol is officially known as Beta Persei, or the second-brightest star in Perseus. In the case of Algol, there is a problem. It isn’t always the second-brightest star. Algol is a variable star, decreasing and increasing in brightness with a very regular period of just a bit less than 3 days. This was a phenomenon that was readily observable by the ancients, but they had no explanation for it. They called it the Demon Star, Gorgona, ...

ANDROMEDA IN THE NOVEMBER SKY

Astronomers estimate that the presently observable universe contains about one hundred billion galaxies. These are very large groups of stars (see the 10/07/19 article by James Lewis) held together by gravity. They exist in difference shapes and can be spiral, elliptical, lenticular, or irregular.   Our own galaxy, the Milky Way, and its nearest full-size neighbor, the Andromeda galaxy, are both spiral galaxies. We used to think that the Andromeda galaxy was two to three times as large as our galaxy, but recent (2018) radio astronomy data shows that they are about the same size. The Andromeda galaxy is about two and one-half million light ...

OBJECTS IN THE SKY

The best times for viewing stars and planets in September 2019 are the beginning and ending days of the month. A new moon occurs on August 30 and again on September 28 when Earth’s moon is so close to the Sun that they both set at almost the same time. Skies will be darker at these times. In contrast, a full moon occurs on September 13, making it more difficult to see fainter objects.   September is a good time to see the Summer Triangle, an asterism of three of the brightest stars in the sky. An asterism is a group of stars that are associated in some way but are not considered to be a constellation.   Even when the moon is ...