Download PISGAH Text by Dr. Bob Hayward ASTRONOMICAL Astronomer

PISGAH
ASTRONOMICAL
RESEARCH
INSTITUTE
Text by Dr. Bob Hayward
Astronomer/Educator
Graphics by TheSky
Software Bisque
Mountain Skies
May 16, 2016
MARS RIVALS JUPITER IN BRIGHTNESS
The planets: In the last column we ignored all the planets except for the elusive Mercury that
transited the sun, i.e., it moved between earth and the sun, on May 9. Mercury has now moved into the
morning skies but is really much too low in the morning twilight to be seen. The same is true of Venus
the brightest of the planets although in the opposite direction. While Mercury was passing from east to
west in front of the sun and moving from the evening to morning skies, Venus has moved eastward
towards the sun and is now lost in the morning twilight. On June 6 it will pass behind the sun and
emerge into the evening twilight. We will start to see it low in the west after sunset in late July. It will
rise higher each night and soon become our brilliant “Evening Star” for the rest of the summer and
beyond.
The real show is happening in the evening skies now. The bright Jupiter stands well up in the
southeast above the waxing gibbous moon. Until Venus joins the evening parade, we will refer to this
giant planet as our “Evening Star.” Shortly before 9 p.m. the bright Mars rises in the east. We don’t
normally refer to Mars as “bright” although it is a naked eye planet. However, Mars is moving closer to
us and on May 30 it will be at its closest for this time around the sun, a mere 46.8 million miles from
earth. Thus, it will appear larger in a telescope and, of course, especially bright.
However, Mars is not alone in our evening skies for long. By 9:30 p.m. the ringed planet Saturn
will be rising and should be well up by 10 p.m. The earth is also getting closer to this beautiful ringed
planet and will experience its closest approach on June 3. But at 838.2 million miles from the earth
Saturn is decidedly more distant than Mars. Because of that, its brightness does not increase as
dramatically as that of Mars and Saturn will nowhere near rival the brilliant Jupiter in brightness. As
mentioned in the last column, Mars and Saturn form a nice triangle with the bright red star Antares that
marks the heart of the scorpion.
The stars: This is a good time of the year to observe the Big Dipper also known as the Drinking
Gourd. Early in the evening, we can find it high overhead in the north lying with the dipper open
downward; and, by 3 a.m. it will have swung over to the northwest. Since the Little Dipper is below the
Big Dipper in the early evening, it appears that the Big Dipper is “pouring” its contents into its smaller
namesake. With the exception of the stars at the end of the handle and the tip of the bowl, the
remaining five stars in the Big Dipper are all at approximately the same distance from us, about 80 light
years. This is a bit unusual since most celestial patterns consist of stars that lie at vastly different
distances.
The dipper is important because it is an easily recognized pattern that we can use to find other
stars in the sky. There are several common “tricks” involving the dipper. First, and most important, is
finding the North Star, Polaris. Locate the two stars that mark the end of the bowl of the dipper. Then
draw a line between them and extend it five times their separation in the direction of the open end of
the dipper. Following this line, you will come to the North Star.
The Big Dipper is not one of the 88 official classical constellations. Instead, its invention is
particularly American. In other countries and traditions around the world, this obvious pattern is known
as the plough (England), Charles’ wain or wagon (Scotland) or a bear (many Native American cultures).
Officially, it is the hindquarters and the long, bushy tail of Ursa Major, the Great Bear. Astronomers
would call the Big Dipper an asterism, not a constellation.
Celestial Calendar:
May 21, 5:14 p.m. EDT – Full Moon
May 19, 8:12 a.m. EDT – Last Quarter
May 30, 6 p.m. EDT – Mars closest to the Earth
June 4, 11 p.m. EDT – New Moon
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PARI is a public not-for-profit public foundation established in 1998. Located in the Pisgah
Forest southwest of Asheville, NC, PARI offers educational programs at all levels, from K-12 through
post-graduate research. For more information about PARI and its programs, visit www.pari.edu.
Follow PARI on Twitter at http://twitter.com/Astronomy_PARI. “Like” PARI on Facebook at
www.facebook.com/Pisgah.Astronomical.Research.Institute.
For further information or questions about this Mountain Skies column, contact Dr. Bob Hayward
at [email protected]. Graphic produced with TheSky by Software Bisque.