Updated October 16, 2018
Nearly one month into northern hemisphere autumn and the days are much shorter than they were in the summer. The sun sets earlier and earlier and the weather is getting cooler. The lead objects of the “planet parade” have or nearly have vanished from view. Venus is no longer visible in the evening sky as it sets around the same time as the Sun. It will pass just underneath the Sun on October 26 and pop up quickly in the morning sky, being visible to those who have clear skies and flat eastern horizons by the first of next month. Binoculars will help to find Venus more easily.
As it gets dark the first objects to “come out” are Mars in the South-Southeast, and Jupiter, low in the Southwest. The waxing crecsent Moon passed Saturn on the evening of October 14 (as seen in North America) and, as a waxing gibbous, will pass Mars on the evening of October 18 (as seen from Asia). The Moon passed first quarter on October 16. Mars is the brightest object in the evening sky but it a lot dimmer than it was back in its late July peak. Jupiter has also faded from its peak brightness as well but can still be seen in the southwest much brighter than its neighbors. Contrast the color of the two objects: Mars appears orange-yellowish while Jupiter is a creamy-white.
Deneb can now be found near the zenith at nightfall as it gets dark at mid-northern latitudes. Vega is further down toward the northwest and Altair is high in the south. These three make up the “Summer Triangle” asterism which now lies high in the western sky and lingers well into fall. Below Altair is the constellation Capricornus which is due south (Sagittarious was due south last month), which hosts Mars in the middle of its boat-like form. Saturn is in Sagittarius and both it and the constellation are sinking lower and lower in the southwest with each passing evening. I noticed last weekend that Mars, Altair, and Vega made more or less a straight line. Check out the situation to see if that’s the case next time it is clear in your location
The Big Dipper is now horizontal in the north as night falls, but is starting to become more easily visible at dawn, standing on the end of its handle in the northeast. Depending on your latitude you may be able to see the Dipper just above the northern horizon (true for those near 40 degrees north) or partially hidden behind the horizon (as is the case at 30 degrees north). From Miami and points south (26 degrees north and further south) the Dipper is just below the northern horizon out of view. The “M”shape of Cassiopeia is nearly due north as it passes upper culmination several hours after dusk. Its presents heralds the constellations of fall, one of which is Pegasus. The Great Square Asterism of Pegasus is standing on one of its corners as seen by an east-facing observer shortly after nightfall.
Mars remains a prominent object in the evening sky, well up as it gets dark. The planet continues to fade, though, as it moves away from the Earth (or more realistically as the Earth moves away from the planet in its smaller, faster orbit). The global dust storm which has been raging on Mars the past several months, continues to subside with surface features being more easily seen through high powered telescopes. More about this dust storm can bee read t http://www.astronomy.com/news/2018/06/mars-storm-2018 and at http://mars.jpl.nasa.gov. Currently the planet is shining at magnitude -1.1, down from -2.8 on the July 27 opposition. This is now fainter than Jupiter which is -1.3 and the brightest nighttime star Sirius which is -1.5. On October 17 the Moon is right of Mars; on the 18th it is left of Mars. Think about it: the moon is a quarter million miles away and Mars sits 260 times further away from us than the Moon.
The annual Orionid meteor shower is active the week of October 21; specifically it is most active on October 21 and 22 but can be seen at nearly peak intensity two more days either side of the two most active days. This shower gets its name from the fact that the radiant, or point of origin of the meteors, appear to trace back to the top part of the constellation Orion. The dust bits that make these slow, graceful shooting stars came from Comet Halley centuries and millennia ago. However, the shower, at peak, only delivers about 20 meteors per hour as seen under perfect conditions which include a dark, rural moonless sky. The Moon is a waxing Gibbous during the peak of the Orionids but should set early enough to allow at least an hour or two (the earlier in the activity peak, the better) of dark skies for viewing.
The Moon is full on October 24th and it is sometimes referred to as the Hunter’s moon. Informally this is known as the Harvest Moon. Read more about the unique history of this designation and more at https://www.universetoday.com/61121/hunters-moon/.
More information on what can be seen in the sky on a weekly basis can be viewed at the website http://www.skyandtelescope.com/observing/ataglance. One can go directly to this week’s information by clicking on the link for this week’s (October 12-20, as of this writing) sky-at-a-glance. For subsequent weeks the most current week is at the top with earlier weeks archived in reverse chronological order.
Due to construction of the observatory addition we have not been able to do any further work on the solar observatory telescope. Once this project is complete, the Prairie View Observatory Complex will house 3 domes, including the existing Solar Observatory, and two new domes. For updates on this progress check out https://www.pvamu.edu/pvso/cosmic-corner/project-summary-2/. Also, more information and images about the expansion (along with the existing Solar Observatory) at https://sites.google.com/view/saganti-astro/home. The two new domes will house our Meade 16-inch advanced telescope and a new 0.6 meter (24-inch) PlaneWave Corrected Dall-Kirkham telescope. The design features these two domes situated east and west of a visitor’s center, which is immediately north of the existing Solar Observatory. First light for the new observatory could happen as early as Spring 2019. Keep checking back for updates.
Juno made its 15th perijove flyby of the planet Jupiter earlier this month and continues to send back spectacular images. You can find them at https://www.missionjuno.swri.edu/junocam/processing?ob_from=&ob_to=&phases%5B%5D=PERIJOVE+15&perpage=16. Last year, Juno flew closer to the Great Red Spot on Jupiter than any spacecraft in history, and this year it has been approved to continue orbiting Jupiter until at least July 2021. For more information about this mission in general visit www.nasa.gov/juno. You can also visit http://www.cnn.com/2016/06/30/health/juno-jupiter/index.html which has some additional interesting facts about the mission.