Monday-Tuesday, October 5-6 all night – Mars closest to Earth
A week before Mars officially reaches opposition, Earth and Mars will be at their minimum distance apart during the early hours of Tuesday, October 6. At that time, Mars will be 38.57 million miles, 62.07 million km, 0.515 Astronomical Units, or 3.45 light-minutes distant from Earth. After Mars rises in the east on Monday evening, observers with backyard telescopes can expect to see the planet with more detail than it will exhibit for 15 years – especially after midnight, when the planet will climb highest in the sky. Viewed in a telescope Mars’ maximum apparent disk diameter will be 22.6 arc-seconds. (For comparison, Jupiter’s disk spans about 44 arc-seconds.) Its Earth-facing hemisphere that night will display its bright southern polar cap, the dark Syrtis Major Planum and Tyrrhena Terra regions, and the lighter toned Hellas Planitia region. The planet will not be as close to Earth for another 15 years.
Wednesday, October 7 evening – Draconids meteor shower peaks
The Draconids Meteor Shower, which runs between October 6 and 10 every year, will peak overnight on Wednesday, October 7. This shower, generated by debris dropped by Comet 21P/Giacobini-Zinner, usually delivers relatively few meteors. But it has occasionally been much more prolific. The best time to watch for Draconids will be after dusk, when the shower’s radiant in Draco will be sitting high in the northern sky. Unfortunately, a bright, waxing gibbous Moon will wash out many of the fainter meteors after it rises at 10 p.m. local time.
Friday, October 9 at 8:39 p.m. EDT – Last quarter Moon
When it reaches its last quarter phase at 8:39 p.m. EDT on Friday, October 9 (or 0:39 GMT on Saturday, October 10), the Moon will rise around midnight and then remain visible in the southern sky all morning. At last quarter, the Moon is illuminated on its western side, towards the pre-dawn sun. Last quarter moons are positioned ahead of the Earth in our trip around the sun. About 3½ hours later, Earth will occupy that same location in space. The week of moonless evening skies that follow last quarter will be ideal for observing deep sky targets.
Sunday, October 11 pre-dawn – Waning Moon meets Messier 44
When the waning crescent Moon rises at about 1 a.m. local time on Sunday, October 11, it will be positioned four finger widths above (or 4 degrees to the celestial west) of the large open star cluster known as the Beehive or Messier 44, in Cancer. During the hours before dawn, the Moon’s orbital motion (green line) will carry it somewhat closer to the cluster. To see Messier 44’s stars more easily, hide the Moon just below your binoculars’ field of view (red circle).
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the universe together.