Our Current Sky

Our Current Sky


our-current-skiesWhat’s Up in Southwest Florida’s August Skies: Jupiter, Saturn, Venus, and the Perseid meteor shower peaks August 12th. Plus, 78% solar eclipse locally, max is 2:53 pm August 21st.

[NOTE: A Total Solar Eclipse will cross the United States on August 21, 2017.  Here in Fort Myers, FL, we are not along the path of totality, so we will see a partial eclipse. A full-country Eclipse 2017 USA map is here (opens in new tab).  An alternative map with local times is here (opens in new tab).]

After sunset, shining with a steady light in the southwest is the golden-white planet Jupiter, just to the right of the bright (twinkling) blue-white star, Spica. Jupiter has been visible in our night skies since  April, but it will not be there for much longer — the Sun is getting closer night by night and in late September, we will lose Jupiter in the evening glare.

Well to the left of Jupiter (high in the South) is another planet — Saturn — shining with a steady light at about the brightness of a bright star. With a small telescope, you can enjoy the sight of Saturn’s rings at near-maximum inclination to our line of sight: that’s the best view Saturn ever gives us of its rings. Saturn will be directly above the “curly giant J” of the constellation Scorpius, known to Moana audiences and Hawaiian astronomy buffs as Maui’s Fish-hook.

To the left of Saturn is a group of eight medium-bright stars in the shape of a teapot (give it curved sides to make it look more teapot-like). The handle is on the left and the spout, tipped down a bit, is on the right. The Teapot is made up of the main stars in the constellation of Sagittarius, the Archer.

Again, to see the cool details of these planets, you’ll need a telescope. This year is the right time to look at Saturn through a telescope: it’s at maximum tilt (26.6 degrees) to show the rings off to best advantage. You’ll have a great view of the biggest gap in the rings: the Cassini division. Sounds like a band, doesn’t it? The big gap between inner rings and outer rings was discovered in 1675 by Giovanni Domenico Cassini, namesake of NASA’s Cassini spacecraft. If you waited 7.5 years, those rings would be edge-on and you would be lucky to see them from Earth as a straight line across Saturn’s middle!  Opposition provides the best and closest views of Saturn, its brilliant icy rings and several of its brightest moons.  If you just see one moon near Saturn, that’s Titan. It’s HUGE!  Titan is 50% larger than our own moon. It orbits Saturn about every 16 Earth days. Our moon takes 27.3 days to orbit Earth relative to the background stars, but 29.5 days to go from full to full (because Earth is also moving along our orbit around the Sun during that month!).

By the way, we will be holding an event to commemorate the life accomplishments of the Cassini space probe in September: the spacecraft has been orbiting Saturn since 2004, but now is in its final mission phase. The Cassini Grand Finale has put Cassini on a trajectory that will eventually plunge it into Saturn’s atmosphere and end Cassini’s mission with atmospheric data and a fiery meteor on September 15, 2017. The decision to end the mission this way stems from a desire to keep Cassini from any possibility of crashing into either Titan or Enceladus after it runs out of orbit-adjustment (thruster) fuel. Titan and Enceladus are very special moons, where the possibility of (microbial) life is higher than in most other places in the solar system (except here on Earth, of course!).

Using that telescope I mentioned earlier, you can compare the cloud bands on Saturn to those on Jupiter. Saturn’s cloud bands are much fainter than the dramatic bands of Jupiter. Saturn’s bands vary from almost-white through a pale tan, but Jupiter’s vary from white through deep rusty red and in some spots red-brown. The most important difference here is that Jupiter is more massive AND a faster rotator than Saturn: Jupiter completes a full rotation on its axis in under 10 hours! It’s the fastest-rotating planet in the Solar System, as well as being the largest, so it has a tremendous rotational engine driving the deep views of darker (hotter, deeper, higher-pressure) bands in the Jovian atmosphere. Through binoculars, Jupiter’s four Galilean moons — Io (EYE-oh), Europa, Ganymede and Callisto — are easy to see, but often one of the four will be in front of or behind Jupiter when you look: the inner moons have very fast orbits, so it’s fun to track the changes from night to night.  NASA’s Juno mission recently completed its sixth Jupiter flyby, so you can see some amazing images of the weird polar regions of Jupiter on the June mission website — those are views we don’t get from Earth because we never see the poles of Jupiter (no axial tilt to speak of, only 3 degrees).

Venus dominates the pre-dawn planet lineup and will be brightening in the sky above the sunrise each day, moving farther beneath and to the left (north) of the constellation Orion the Hunter in our predawn sky. Venus rises around 2 am, so Venus really has the end of the night to itself — well, except for the meteor showers. The Pleiades will be dominating the night sky to the north of you starting about 10 pm and the peak of this shower is August 12th: Happy meteor hunting!

Monday Aug 21st , 1:30 pm – 3:45 pm – Solar ECLIPSE Observing (clear skies permitting)
Eclipse Maximum is a 2:53 pm, please arrive earlier if you hope to get a glimpse through the special solar telescope. Live solar observing using the Coronado Solar Telescope: The Graesles will guide you to a view of the eclipse in detail as it progresses from 1:23 pm “first cotact” right through the maximum (78% coverage) at 2:53 pm, and back out the other side… PLUS eclipse glasses will be available for those who wish to watch the progress at real-scale when not looking through the telescope. DO NOT GAZE AT THE SUN WITH NAKED EYES. Will there be sunspots today? Prominences? A flare? Nobody can be sure until the day arrives… Planetarium volunteers from the Southwest Florida Astronomical Society will show you the Sun “live” as few people get to see it. Catch our narrow-band filter’s detailed view of the Sun live on the platform in front of the planetarium for this rare event. If the skies do not cooperate, our Education Coordinator Walter Cheatham will attempt to stream the eclipse from NASA’s internet feed to a computer inside the planetarium: thank you, Walter! Planetarium Director Heather Preston will be live on the path of totality in Wyoming (results of that “remote” subject to technical considerations, we are not a TV network but we will try!)

Moon phases this month:

  • Jul 30     1st Quarter
  • Aug 7      Full
  • Aug 14   3rd Quarter
  • Aug 21    New
  • Aug 29   1st Quarter

Heather Preston, Planetarium Director, Calusa Nature Center Planetarium, Fort Myers, FL

Astronomy News Bulletins:

  • Exploding Supernova will change Cygnus

Calvin College professor Larry Molnar and his students along with colleagues from Apache Point Observatory (Karen Kinemuchi) and the University of Wyoming (Henry Kobulnicky) are predicting a change to the night sky that will be visible to the naked eye.

“It’s a one-in-a-million chance that you can predict an explosion,” Molnar said of his bold prognostication. “It’s never been done before.”

Molnar’s prediction is that a binary star (two stars orbiting each other) he is monitoring will merge and explode in 2022, give or take a year; at which time the star will increase its brightness ten thousand fold, becoming one of the brighter stars in the heavens for a time. The star will be visible as part of the constellation Cygnus, and will add a star to the recognizable Northern Cross star pattern.

Read more at: http://phys.org/news/2017-01-astronomers-explosion-night-sky.html

  • Pro-AmComet Observing Invitation

Get in on the Pro-Am Comet Observing Action! Remember, the campaign starts later THIS MONTH: https://astronomynow.com/2016/11/24/worldwide-pro-am-help-sought-for-comet-trio-study/. The actual page with details is at the Planetary Sciences Institute, here: http://www.psi.edu/41P45P46P

Useful Sites for Backyard Astronomers…

Here is an off-site excellent summary (opens in new page) of night sky observables this month…

The International Space Station is visible some nights, and is very bright! For specific visibility direction, greatest altitude, and time at your location: https://spotthestation.nasa.gov/sightings/

The Hubble Space Telescope is visible some nights.  For specific times and routes: http://www.heavens-above.com/