State Of The Sky On The 4th Of July

My neighbors setting off fireworks. Bob King

America celebrates its independence today. My independent minded neighbors began their festivities days ago, setting off firecrackers and bottle rockets till past midnight. But the big fireworks happens tonight. Most cities start blasting shells into the air around 10 o’clock, about an hour after sundown.

If you’re one of the millions of people who’ll be there, take a look around the sky before the show begins and after you get back home. With clear skies, you can take the opportunity to show your kids and friends what’s up.

Look for Venus (easy!) and Mercury (more challenging) low in the northwestern sky in the direction of sunset tonight. Stellarium

Right now, we can see six planets (Earth included) in the evening sky starting at dusk with Venus and Mercury low in the northwest and Jupiter and Saturn in the south. All are visible during twilight though Mercury departs by 10 and Venus by 11. So if you have an open view to the west, Venus will be obvious to the naked eye and Mercury in a pair of binoculars before the fireworks begin.

About the time the fireworks begin, Jupiter and the Jupiter Triangle should be obvious. Antares and Saturn should appear around 10:15 p.m. local time. Stellarium

Turning your gaze to the south, Jupiter’s will stand out by 9:30-10 p.m. local time gleaming in the southwest. The giant planet forms an appropriately giant triangle, nicknamed the “Jupiter Triangle” with bright Spica to its right and Arcturus above. Once it gets a little darker, say from 10:15 on, look for Saturn low in the southeastern sky.

Look up in the east around 10 o’clock to spy Vega, Deneb and Altair, the stars that outline the asterism called the Summer Triangle. Bob King

Other stars shine bright and steady as the fireworks flare and fade. Over in the east about midway up in the sky, look for another triangle led by brilliant Vega, called the Summer Triangle. There’s also the red luminary Antares, which shines between Saturn and Jupiter. Keep an eye on this one. Like its counterpart Betelgeuse in the winter sky, Antares is a red supergiant star near the end of its life. One day in the not too distant future it will explode as a supernova and shine as brightly as a half-moon.

Antares, brightest star in the Scorpion, is a supergiant on the way to becoming a supernova. Astronomers recently mapped the star’s surface to show heat bubbles rising up from below. It’s the clearest photo of another star yet taken. ESO

By the time you’ve arrived home, around 11 o’clock, Mars peeps over the southeastern horizon trailing Saturn. It’s identical in brilliance to Jupiter and salmon-colored. Not red? Normally, it is but this isn’t a normal year. A huge, planet-girdling dust storm has turned the planet’s color from rusty or pinkish red to a pale orange!

If you out on the wide-open prairie or big lake it’s possible to see four planets — Venus, Jupiter, Saturn and Mars — simultaneously just before 11 o’clock. You’ll have to look way down to the northwest horizon to spot Venus and just above the southeastern horizon for Mars.

Between about 10:45 and 11 p.m. it’s possible to see four bright planets at once. This map shows the sky spanning from southeast to northwest. Stellarium

Let’s see. That leaves just two planets, Uranus and Neptune. They don’t come up till late and require binoculars. We’ll touch on how to see them later this summer. Happy 4th!