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Fans of "two in the view" targets will appreciate M81 and M82, a nicely-contrasting pair of galaxies above the bowl of The Big Dipper. The traditional way to reach them is to draw an imaginary line diagonally across the bowl of The Big Dipper from its lower rear corner to its upper lip, then follow that line one more step to reach the galaxy pair (or more accurately, to reach a distinctive pair of stars just beyond the galaxies). If that works for you, great; but for some reason, I've always had to get there by a more plodding route, using an L-shaped group of stars just above the Dipper as a stepping stone, as shown in the chart below .

• • .. • .. • • Thuban • • .. •

• o~ : •

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- --.------­ Whichever way you get there, these galaxies are a sure-fire treat. You don't need to kill them with magnification: start around 40-50x and build up from there. The brighter one, M81, is a magnitude 6.9 spiral seen nearly face-on, covering 18 x 10 arcminutes of sky. This is probably how the Milky Way would look, as seen from a distant foreign galaxy. Small scopes reveal a bright nucleus surrounded by a fainter splotchy haze, all wrapped inside a grainy oval glow.

M82 lies just over a half-degree north of M81; their separation in space is only about 100,000 light years, which puts them 25 times closer to each other than we are to our nearest major galactic neighbor. At magnitude 8.4 and spanning 8 x 3 arcminutes, M82 is dimmer and smaller than M8l. Under dark skies, binoculars show it as a gray celestial cigar, with M81 appearing as an oval smudge lying to its south. In small scopes, M82 is an elongated streak of haze running east-to­ west, brighter on one side than on the other. More details emerge with larger apertures and higher power, including a dark bar crossing M82's midsection, and subtle hints of spiral structure in M8l.

While you're in the neighborhood, take a minute to go back to that L-shaped group that I use as a marker to find the galaxies. If we take a closer look at the long arm of the L, we'll find a carbon star known as VY Ursae Majoris just about exactly midway between the two bright stars of that arm. Like all carbon stars, VY UMa has exhausted its supply of hydrogen and is now fUSing helium into heavier elements, but since helium fusion produces less energy than hydrogen fusion, the star has become cooler than it used to be, and has taken on a red color due to its lower temperature. On top of that, one of the elements produced by helium fusion is carbon, which hitches a ride on convection currents to reach the star's surface, where it condenses into particles of soot that scatter the outgoing light, just like tiny particles in our atmosphere scatter the light at sunset. Since light scatters more readily at the blue end of the spectrum, this dissipates the blue portion of the star's emitted light, allowing the red end of the spectrum to pass through, and intensifying the star's crimson hue - making it a very attractive sight for us. With a magnitude range of 5.9 to 6.5, VY UMa is a deep red beacon that can be seen in all telescopes, or even with binoculars in a dark sky.

Finally, let's take a journey back in time to 2700 BCE, when the Egyptians were building the pyramids and developing humanity's early understanding ofthe sky and its inhabitants. The North Star of their sky wasn't our now-familiar Polaris, but instead was a mag 3.6 star in Draco known as Alpha Draconis, or Thuban. Although the Egyptians were unaware of it, Earth's axis wobbles through space like a drunken sailor, completing one cycle every 26,000 years. This process, called precession, changes our view of the sky, and makes different stars appear closest to the celestial pole as our axis swings around - which is why our pole star isn't the same one the Egyptians saw.

To find Thuban, draw a line from Gamma to Delta Ursae Majoris - the stars at the back end of The Big Dipper's bowl- and follow it four more steps to a fairly bright star. That's almost the same process as you'd use to find the current North Star, Polaris, but shifting the pointers from the front of the Dipper's bowl to its rear. And if you like the idea of having Thuban as the North Star, all you have to do is wait until the year 23000 or so, and it'll be Thuban again - but not before a whole lot of other stars (including Alpha Cephei, R Lyrae, and Tau Herculis) have all had their turn.

Rick Gering - March 2020