Wednesday, September 16 pre-dawn – Morning zodiacal light for mid-northern observers
For about half an hour before dawn during moonless periods in September and October annually, the steep morning ecliptic favours the appearance of the zodiacal light in the eastern sky. This is sunlight scattered by interplanetary particles concentrated in the plane of the Solar System. During a two-week period that starts just before the September New Moon, look above the eastern horizon for a broad wedge of faint light rising from the horizon and centered on the ecliptic (marked by green line), which extends below Venus toward the bright star Regulus in Leo. Don’t confuse the zodiacal light with the Milky Way, which is positioned further to the southeast.
Thursday, September 17 at 11:00 GMT – New Moon
At its new phase, the Moon is travelling between Earth and the Sun. Since sunlight is only reaching the far side of the Moon, and the Moon is in the same region of the sky as the Sun, the Moon will be completely hidden from view for about a day. Since this new Moon is occurring a day before perigee, the Moon’s minimum distance from Earth, tides will be larger around the world.
Friday, September 18 after sunset – Crescent Moon and Mercury
After sunset on Friday, September 18, sharp-eyed observers might spot the very slim crescent moon sitting just above the western horizon, and a slim palm’s width to the upper right (or 5 degrees to the celestial north) of Mercury. The moon and Mercury will both fit into the field of view of binoculars (red circle) – but ensure that the sun has completely disappeared from view before using them.
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.