What's Up in SW Florida Skies

Inspiring People to Connect with Nature

July 2020: A Lunar Eclipse You Probably Won't Even Notice...and a Comet You May!

SW Florida Astronomical Society Meetings have moved to Zoom while the planetarium is closed for Covid-avoidance. We are upgrading the planetarium and hope to reopen for safety-conscious planetarium shows again soon!

Moon Phases July:

4-5     12      20       27

Full     3Q     New    1Q

The night of the 4th of July, there will be a partial penumbral lunar eclipse. According to NASA, "the slight reduction in the moon's brightness will be difficult to notice with the human eye." If you have very clear conditions, you might notice a slight dimming in a "shallow bite" shape along the Moon's edge. It's nothing like as dark as an "umbral" eclipse.

Comet NEOWISE (designated C/2020 F3 NEOWISE) was discovered on 27 March 2020 by NASA’s Wide-field Infrared Survey Explorer telescope (WISE). It will make its closest pass to the Sun on July 3rd, and from the evening of July 12th on, we may be able to see it low in the NW after sunset: definitely check the evening sky on the 12th, 13th, 14th and so forth!  It’s predicted that this comet could dramatically increase in brightness after perihelion, becoming possibly quite a bright object just after sunset, assuming the comet doesn't "fall apart" during its perihelion encounter!  If you are an early riser, you can catch NEOWISE earlier in the month: it will climb higher in the predawn sky from July 5th on, reaching about 10 degrees above the northeast horizon around July 11. The comet will then be lower and lower predawn NE-ward over the following10 days, eventually disappearing beneath the predawn horizon: but by that time, you will be able to see it NW-ward in the early evening. On July 22, NEOWISE makes its closest approach to the Earth, at a distance of 64 million miles (103 million km). By July 25, the comet will appear 30 degrees up from the west-northwest horizon just after sunset.

Also in the early evening as it gets dark, look to the West to bid farewell to the beautiful constellation of Leo. It looks like a backward question mark, with a triangle southward and slightly higher. Once it's fully dark, look SSE for the "curly J" shape of Scorpius, whose curling tail sits just below the center of the Milky Way's galactic band as you gaze southward. If you have a very flat southern horizon (say, from the beach looking south toward the Keys), you may see a yellow star with a slightly dimmer blue star to its right. That yellow star is Alpha Centauri, part of a trinary system and our nearest stellar neighbor in the entire Milky Way galaxy: the nearest component of the Alpha Centauri system, a dim star called Proxima, is only 4.2 light-years from our solar system!  For scale, the solar system is light-days across, and the Earth is eight light-minutes from the Sun.

The predawn sky (about 6 am) is where it's at for viewing the largest number of planets! Venus shines brilliantly in the east-northeast; in mid-July it's beside the bright orange star Aldebaran (in Taurus) and on July 17th, it's beautifully accompanied by the thin waning crescent moon. At the same time, look high in the South to see butterscotch-rusty Mars, and continue scanning to the west to find Brilliant Jupiter and not-as-brilliant Saturn medium-low in the SW sky.

Late July into early August, Mercury will return to the pre-dawn eastern sky. Between July 20th and August 4th, Mercury will brighten significantly, rising as much as 60 to 70 minutes before the Sun.


During this month, you will probably notice a bright triangle of stars high in the sky after 11 pm, and rising 4 minutes earlier each day: The Summer Triangle of Vega, Deneb and Altair! As for rising 4 minutes earlier each day, all stars do: Earth orbits the Sun about 1 degree per day to make our full circle in 365.25 days. To make up for that one extra degree of rotation Earth has to cover to reach the same "solar" time, Earth must rotate for an additional 4 minutes of time on its axis. So a star-based, sidereal day is 23 hours 56 minutes, while a solar day (noon to noon or midnight to midnight, for example) is defined as 24 hours. There are a few more things that happen with Earth's rotation and orbit, but those are the basics! The beautiful part of recognizing the Summer Triangle is that it also straddles the brighter part of Milky Way, so if you were wondering where the plane of our galaxy is, it passes through the Summer Triangle and through the "curly J" shape of Scorpius, south of the Triangle.

For people who love watching satellites brilliantly and slowly pass through our skies, follow the "Spot the Station" link below.

Remember, once we reopen, every Friday if it's not cloudy we will have our solar observing expert Gordon once again (I surely hope!) showing you the Sun "live" through our Coronado Solar Telescope in front of the Planetarium at 11 am. The wonderful planetarium astronomer Carol will be ready to show you the Universe at Friday's shows, as well, and dashing Bruce Dissette will be presenting shows on Saturdays, with our newest planetarium educator, Todd Sherman, presenting the Sunday shows. So take good care to help flatten that curve, and we will see you again soon in the Planetarium!

To spot the International Space Station moving through your sky, try NASA's Spot The Station website! Or to add in the Hubble and various other bright satellites, you can try Sky & Telescope's Tracker page.

Hoping to see you soon at the Center,

Heather Preston, Planetarium Director

© 2020 by CNCP