In May, as the Sun continues to set later and later, and further and further toward the northwest, the twilights are longer and so the nights are shorter. This doesn't usually bode well for astronomers and stargazers, but as long as you're not north of about 55 degrees north latitude, the night sky is still dark and there's always plenty to see.

If you go outside at about 10 in the evening, the sky may not be as interesting now, in terms of the number of bright stars and planets, as it was a couple of months ago. However, because it's warmer, we're much more inclined to inspect the skies a bit more carefully and not just take a casual glance and then have to dash back inside before we freeze our fingers and toes. Perhaps the most obvious and brightest of all the constellations in the Northern Hemisphere, Orion, is now gone from the evening sky, and a parade of familiar winter constellations will soon sink with the setting Sun. However, right now Gemini (the Twins), Canis Minor (the Little Dog) with its bright star Procyon and Auriga the (Chariot) with its magnificent white star, Capella, are near eye-level about an hour after sunset in the western sky.

Our nearest neighbors are a tad on the bashful side now. The moon is a waning crescent, rising after midnight, Venus is a "morning star," only visible at dawn, and Mars is very low in the southern sky, and not very easy to see. Although Saturn has already fallen below the western horizon at dusk, Jupiter is very bright, low in the west at dusk, and to its upper right is the elusive Mercury. Because Mercury is closer to the Sun than are the other planets, when it's visible, it's seen hovering near the Sun, either just after or just before sunset.

In the eastern sky, the constellations we see overhead in summer are peeking above the horizon as darkness falls. The bright star, Vega, shines brilliantly in the northeast, waiting for the other summer stars to take their place.

The three most prominent spring constellations, Bootes (the Kite), Virgo (the Virgin Queen) and Leo (the Lion) ride high in the sky in mid May. Actually, only Leo is easy to identify - a question mark shape is its head and chest with the bright star Regulus as the dot at the bottom of the ?, and a triangle of 3 stars is its hind quarters. Both Bootes and Virgo have only one bright star a piece, Arcturus and Spica, respectively.

The reddish-orange Arcturus is the brightest star in the spring sky and one of the biggest stars visible form our part of the galaxy. It makes our Sun look puny - 25 million Earth's could fit inside of it. Its light comes to us from about 36 light years distant. Arcturus actually opened the World's Fair in Chicago in 1933! The idea was to focus its light through a telescope and onto a photocell, which tripped the lights used to open the fair. Because a previous World's Fair was held in Chicago in 1893, and because it was though that Arcturus was 40 light years distant, the same light that left the star at the end of the last World's Fair would just be arriving at the start of the 1933 fair - a neat idea even if the measurements were off a little.

While Arcturus is the most noticeable star in the spring sky, the honor for the most conspicuous constellation has to go to Ursa Major, aka the Big Dipper. Actually, the Big Dipper is an asterism, its stars form a segment of the larger groping of stars that form Ursa Major (the Big Bear). The Big Dipper is high in the sky at this time of year. At the end of evening twilight last night, the Big Dipper reached its highest point in the sky. A casual glance suggests that it's overhead, but it's really only about three-quarters of the way up.

The Big Dipper is one of a handful of circumpolar constellations visible in the Northern Hemisphere - they're each visible every night of the year for residents north of about 30 degrees north latitude. Ursa Minor (the Little Dipper), Cephus (the King), Cassiopeia (the Queen), and Draco (the Dragon) are the other well know circumpolar constellations. During the course of the night, these constellations twirl about the north celestial pole. This is basically the imaginary axis, about which the Earth rotates, that extents through both the North Pole and the South Pole. The circumpolar stars rotate counterclockwise about the north celestial pole, and the star closest to this imaginary axis is the North Star or Polaris. So, during the course of the night, Polaris seems to remain almost stationary, while the other stars spin around it.

Polaris, is a second magnitude star, meaning that first order magnitude stars, such as Arcturus or Regulus are about 2.5 times brighter, and third order magnitude stars, such as the star next to Polaris, in the Little Dipper's handle, are 2.5 times dimmer. On a clear night, most people can see 5th order magnitude stars with the unaided eye. Though far from the brightest star in the sky, Polaris is one of only two second order magnitude stars in the Little Dipper, and it's easy to find since the end stars or pointer stars of the dipper in the Big Dipper point very close to it.

None of the Big Dipper's stars are first order magnitude either, but 6 of the 7 stars that compose the dipper and handle are second magnitude. Because these stars are all about the same brightness and appear to be about the same distance from each, our eyes are drawn toward them. Plus, we can see the Big Dipper on any cloudless night of the year. Because of these attributes, the Big Dipper has long been used as a map or guide to help find our way around the night sky. We've already mentioned that the pointer stars in the dipper can be used to locate Polaris and, thus true north. In addition, the graceful arch of the Big Dipper's handle directs us to Arcturus (it's name has nothing to do with this), and then on to Spica. Furthermore, the first 2 stars forming the left part of the dipper, lead toward Regulus (in the opposite direction from Polaris), and the top 2 stars of the dipper point toward Capella.

When we look toward the Big Dipper, we're looking away from the plane of our galaxy, and this is why there are fewer stars in this part of the sky. This is the direction one would go to escape the Milky Way, and it offers a fine view to astronomers who want to study other galaxies without having to first peer through the dust and clutter of our home galaxy.

In's intriguing that a number of ancient cultures could find a bruin in the grouping of stars that compose Ursa Major. The Greeks, Native Americans and people from northern Europe all saw it as a bear - the handle is supposed to represent the tail. The stars that form the head and feet are very faint (3rd, 4th and 5th magnitude). Just about anything could be drawn from this grouping of stars, so it's still a mystery how cultures isolated geographically from each other could each see a bear. While most Americans see a dipper rather than a bear, many people from England see a plow. A plow makes sense since this is the time of year for plowing and planting.

To test your vision, see if you can see the middle star in the Big Dipper's handle, Mizar, and it's smaller companion as well, Algor. This is the most famous double star system. They're sometimes referred to as the horse and rider. If you live in a fairly remote area, see if you can discern the spiral galaxy known as M81 without the aid of a telescope or binoculars. It can be found to the upper right of the pointer star closest to Polaris, named Dubhe (pronounced Dubby). M81 is about the dipper's width from Dubhe. If you can spot this distant jewel, you're eyesight is good to about 10 million light years - you probably don't have to be concerned about wearing glasses anytime soon.

For more about this see the Abrams Planetarium web site, http://www.pa.msu.edu/abrams/diary.html  and the book Secrets of the Night Sky by Bob Berman.