Here’s a tricky one, especially if you live north of the equator. Australian observers will have a good chance of being able to see the waning crescent Moon close to Mercury in the pre-dawn sky, but those in the United Kingdom and North America might be out of luck. Australian observers should look to the east while northern hemisphere observers will need to look toward the south-eastern horizon.
(Click on an image to enlarge.)
Images Courtesy of Mobile Observatory.
04:34 UT – The waning crescent Moon passes Mercury. (Mercury: 44% illuminated, magnitude 0.3, diameter 7.9”. Capricornus, pre-dawn sky. See image above.)
15:18 UT – The waning crescent Moon passes asteroid 4 Vesta. (Vesta: magnitude 7.6. Capricornus, not visible.)
Venus brightens to magnitude -4.0. (89% illuminated, diameter 11.6”. Pisces, evening sky.) It is quickly catching up on Mars. The pair will form a very close conjunction on the 21st with the waxing crescent Moon appearing close by on the evening of the 20th.
Learn more about every upcoming astronomical event in 2015 An Astronomical Year (Kindle eBook) and The Astronomical Almanac (2015-2019) (Kindle eBook) and The Astronomical Almanac (2015-2019) (Paperback Edition).
The Amateur Astronomer’s Notebook allows astronomers to log 150 observing sessions and includes an appendix of hundreds of suggested deep sky objects.