Our Current Sky

Our Current Sky

our-current-skiesWhat’s Up in Southwest Florida’s October Skies: Meteors. Asteroid TC4 close pass. Plus: Jupiter, Saturn, Venus, Mars but bye to Mercury (for now)…

Just after sunset, shining with a steady light very low in the west is the golden-white planet Jupiter. 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 by mid-month we will finally lose Jupiter in the evening glare.

As soon as it gets dark, medium-high in the Southwest 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.

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!  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!).

  • October 5Full Moon. This means the Moon is directly opposite the Sun in Earth’s sky and so is fully illuminated as seen from Earth. This phase occurs at 18:40 UTC. This full moon was known by early Native American tribes as the Full Hunters Moon because at this time of year the leaves are falling and the game has put on its fat to last through winter. This moon has also been known as the Travel Moon and the Blood Moon. In agrarian cultures, this moon is also known as the Harvest Moon. The Harvest Moon is the full moon that occurs closest to the September equinox each year.
  • October 8Draconids Meteor Shower. The Draconids is a minor meteor shower, so it produces only about 10 meteors per hour. The meteors’ streaks are produced by dust grains ejected from comet 21P Giacobini-Zinner on its last pass through the inner solar system. Giacobini-Zinner was first discovered in 1900. The Draconids is unusual for a meteor shower in that the best viewing is in the early evening instead of after midnight (as is true with most other showers). The shower runs annually from October 6-10 and peaks this year on the the night of the 8th. Unfortunately, the light of the nearly-full moon will drown out all but the brightest meteors this year. If you are extremely patient, you may be able to catch a few good ones. Best viewing will be in the early evening from a dark location far away from city lights. Meteors will generally radiate from the constellation Draco (north, between the Big Dipper and the Little Dipper), but due to random motions of the dust grains from the comet’s orbit, they can appear anywhere in the dark sky.
  • October 12 –  TC4 Asteroid Close Pass. TC4, an asteroid measuring between 50 feet and 100 feet in length will pass Earth today at a distance of 27,000 miles — about 12.5% of the distance to the Moon. This is far enough away to miss the large group of geostationary satellites which orbit around 22,236 miles above Earth. TC4 was discovered in 2012 and astronomers tracked it until it got too faint to detect – now astronomers at the European Southern Observatory recently made the first “reacquisition” direct observations of the object. These new views of the asteroid have allowed experts at NASA’s Center for Near-Earth Object Studies (CNEOS) to refine its orbit and the distance at which it will make its closest approach. The asteroid is currently traveling at a speed of 30,000mph and while it appears very dim at the moment, it will get brighter as it gets closer. Tracking TC4 will be considered a test of the worldwide cooperation required for a “planetary defense system” against asteroid impacts to become a reality.
  • October 19New Moon means the Moon is between Earth and the Sun (not perfectly, or there would be a solar eclipse again!), so of course the New Moon is never visible in the night sky. This phase occurs at 19:12 UTC. New Moon is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to make the sky too bright to see the faint stuff.
  • October 19Uranus at Opposition. The blue-green planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. Although this is the best time to view Uranus, it is NOT visible to the naked eye, or even to most binoculars: it will only appear as a tiny blue-green dot in all but the most powerful telescopes.
  • October 21, 22Orionids Meteor Shower (awesome sauce!). The Orionids is a moderate-sized shower, typically producing up to 20 meteors per hour at its peak. It is produced by dust grains left behind by comet Halley, which has been known and observed since ancient times. The shower runs annually from October 2 to November 7. It peaks this year on the night of October 21 and the morning of October 22. During the peak nights, there’s a thin crescent moon which will set early in the evening, leaving dark skies for good meteor shower viewing. As with most meteor showers, the best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Orion (low in the East at midnight, rises around 11 pm), but again because of random motions within the orbital band, Orionid meteors can appear anywhere in the sky.

Orion, king of the winter constellations, starts making an appearance after 11 pm in the eastern sky right up to dawn, followed by his two hunting dogs, one of which (Canis Major) contains the brightest star in our night sky, Sirius (the Dog Star).  Below and to the left of Orion, the planet Venus shines brightly under the “backwards question mark” of Leo the lion.

Venus dominates the pre-dawn planet lineup and will be bright in the sky above the sunrise each day, moving downward from just above, to beside, to beneath the dimmer, redder, planet Mars on October 4th, 5th and 6th respectively in our predawn eastern sky — you can see this anywhere from 6 am to 6:30 or so low in the east if the eastern horizon is clear. Near Venus, that reddish-orange dot that shines with a steady light is Mars (almost at the far side of its orbit, so not as bright as it gets by any means), but Mercury has now left our pre-dawn dark sky and is back within a few degrees of the Sun, in an area too bright to see.  It may peek out by the end of the month (Oct 31) very low in the west for just a few minutes after sunset, but November is a better bet for catching another sight of early-evening Mercury.

  • Oct 5      Full
  • Oct 12   3rd Quarter
  • Oct 19    New
  • Oct 27   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/