The summer of 2010 begins Monday — at least astronomically — with the summer solstice at 6:28 a.m., and it'll be the longest day of the year.

Monday is the day the sun reaches its highest height in our Western Pennsylvania sky. It all has to do with the inclination or tilt of Earth's axis as it orbits the sun. Monday also is the day our northern hemisphere receives the maximum amount of solar radiation as the noontime sun shines directly over the Tropic of Cancer. That line of latitude is 23.5 degrees north of the equator. Here in Butler at 41 degrees latitude, our noontime sun won't be quite at the zenith, but it'll be close at just more than 72 degrees above the southern horizon.

The sun rises in the northeast at 5:48 a.m. and sets in the northwest 15 hours and seven minutes later at 8:55 p.m. Also, because the sun is taking such a high arc across the sky, morning and evening twilight goes on a lot longer than it does in winter. All of this doesn't leave much night for summer stargazing.

Making the stars your old friends this time of year also is a challenge because there's much more humidity in the air that can really "muddy" up the visibility as the added moisture amplifies the effects of light pollution. And then there's the mosquitoes, but don't let that stop you. They love to bite, but usually an hour or so after sunset, they leave you alone.

Despite all these challenges, the obvious advantage for summer stargazing is you're not freezing your derrière or any other body parts off. In fact, I highly recommend sometime this summer you spend an extended time under the summer canopy of stars and maybe even stay out all night. Trust me, it can really be good for your soul. Go ahead and search for targets in your telescope, but also just sit in silence lying back in a lawn chair with and without a star map and pan your eyes among the constellations in the celestial dome.

For extra credit, if you stay awake long enough, take in morning twilight. For this, I want you to take the advice of Jack Horkheimer, longtime host of the weekly PBS show "Stargazer." Relax, sit back and face the northeast about an hour before sunshine and take in all the sights and sounds. No cell phones, no radio, just you and your senses. I've done this a number of times and simply love it! You don't have to haul off to some exotic location either. Your own neighborhood is just fine, be it urban or rural.

As nice as it is, I don't recommend you set off on your all-night star-watching adventure for the next week to 10 days because the first full moon of the summer is taking over the night sky. The actual date of the exact full moon is Saturday, but all this week, our lunar neighbor will be washing out the celestial dome with its secondhand reflected sunshine.

You can't but notice the full or near full moon this time of year takes a low track across the southern sky. In fact, it takes pretty much the same low path the sun does around the winter solstice, the first day of winter.

That makes sense because the geometry of the full moon is such that it's always on the opposite end of the sky from the sun, so this time of year while the sun takes its high arc across the sky, the full moon is a low rider. Around the winter solstice in late December, there's a flip-flop. The sun takes its low trajectory in the southern sky, and the full moon around Christmas is a high archer.

If you're up early Saturday morning before sunrise enjoying the full moon before it dips below the southwestern horizon, you'll witness a lunar power failure. Just before moonset just after 5 a.m., you'll notice the upper half of the moon will darken. That's the result of a partial lunar eclipse as the moon in its orbit around the Earth slides across the upper portion of the Earth's shadow.

This can only happen when there's a full moon, but it doesn't occur every full moon because the plane of the Moon's orbit around the sun is inclined by five degrees from the Earth's orbit around the sun. So during most full moons, the moon either passes above or below the Earth's shadow against the sun. But this time around, the moon is just catching the edge of the shadow.

Later this year, on the first morning of winter, Dec. 21, there will be a much more magnificent total lunar eclipse. Mark that on your calendar!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and author of the book "Pennsylvania Starwatch", available at bookstores and at his website www.lynchandthestars.com.