Astronomicalastronomer/Educator

PISGAHText by Dr. Bob Hayward

ASTRONOMICALAstronomer/Educator

RESEARCHGraphics by TheSky

INSTITUTESoftware 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 theDrinking 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 starsin 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 ofUrsa 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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For further information or questions about this Mountain Skies column, contact Dr. Bob Hayward at . Graphic produced with TheSky by Software Bisque.