Appendix A Timetable of Celestial Events through 2020 The following pages contain an astronomical almanac for the years 2011 through 2020. Think of it as a “program guide” to the sky. It lists the most observable celes- tial happenings – including the Moon’s phases, lunar and solar eclipses, planetary gatherings and much more – in order of their occurrence. To preview what’s in store for each year, read the year’s highlights preceding each annual listing. To find out what’s happening on a given day, check the nearest date in the almanac. Events discussed or illustrated within the book contain a reference to the page number where you’ll find a diagram or more detailed information. Some events not visible to the naked eye, such as planets in conjunction with the Sun, are included to assist you in understanding when a planet is transitioning from the evening to the morning sky or vice-versa; others, such as Mercury transits and Earth’s extreme distances from the Sun, are included for their intrinsic interest. Throughout the book, we refer to the brightness of the planets and stars by refer- ring to the standard astronomical magnitude scale (detailed in Table 1.1 on page 8 ), usually by giving an object’s magnitude parenthetically after the object’s name – for example, Mars (1.2) or Saturn (−0.3). Keep in mind that the smaller the number, the brighter the object. Venus, the third brightest object in the sky, always has a negative magnitude around −4.0. This is so bright that, when seen in twilight or a dark sky, Venus looks artificial and much closer than it really is. Understanding Time The text refers to time in numerous ways. Some of these references depend on geographic location, while others do not. F. Reddy, Celestial Delights: The Best Astronomical Events through 2020, 303 Patrick Moore’s Practical Astronomy Series, DOI 10.1007/978-1-4614-0610-5, © Springer Science+Business Media, LLC 2012 304 Appendix A Use previous calendar date de of . m m m . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. p.m. a.m. a.m. p.m. p.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. 2 3 4 Hawaii Hawaii (HST) UT– 10 6 5 4 3 2 1 8 Midnight 7 10 9 10 9 1 Noon 8 7 6 5 . m m m . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. p.m. a.m. a.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. p.m. p.m. 3 4 5 Alaska (AKST) UT– 9 7 6 5 4 Midnight 11 3 2 1 8 10 9 10 9 2 Noon 1 11 8 7 6 . m m m . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. a.m. p.m. a.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. p.m. p.m. 4 5 6 Pacific Pacific (PST) UT– 8 8 7 6 5 1 4 Midnight 11 3 2 9 10 10 9 3 Noon 11 1 2 8 7 . m m m . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. a.m. p.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. p.m. p.m. 5 6 7 Mountain (MST) UT– 7 moment of a calendar day 8 7 3 6 2 5 1 Midnight 11 4 10 9 10 9 4 1 Noon 11 2 3 8 . m m m . last a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. p.m. p.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. p.m. 6 7 8 Central (CST) UT– 6 8 4 7 3 6 2 1 Midnight 11 5 10 9 10 9 5 2 1 3 4 Noon 11 . m m m . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p.m. p.m. p.m. p.m. p.m. p.m. p.m. p.m. p p.m. p p.m. p p.m. 7 8 9 Eastern (EST) UT– 5 5 8 4 7 3 2 1 6 Midnight 11 10 9 10 Noon 11 6 3 2 4 5 1 . m m m Convert universal time to U.S./Canadian standard time zones time to U.S./Canadian standard zones universal Convert . a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. a.m. p p.m. p.m. p.m. p.m. p.m. p.m. p.m. p.m. p.m. p p.m. p p.m. 0 7 8 9 Atlantic (AST) UT– 4 h 1 10 17h 1 16h Noon 11 15h 11 14h 10 10h 6 13h 9 9h 5 12h 8 8h 4 *As used in this book, “midnight” refers to the add one hour to the clock time indicated by this table. Note that neither Arizona (outsi When in effect, Time. Daylight Saving they countries recognize some form of “summer time,” While many Time. Daylight Saving observes Nation) nor Hawaii the Navajo do not necessarily change their clocks on the same dates as U.S. 23h 20h 4 19h 3 7h 3 6h 2 11h 7 21h 22h 5 6 18h 2 Table Table A.1 UT 0h 1h 2h 5h 1 4h Midnight* 11 3h 11 Understanding Time 305 Horizon scenes. Illustrations throughout the book show the changing positions of the Moon and planets as seen by observers in the United States and southern Canada at the times and dates noted in the captions. For observers elsewhere in the Northern Hemisphere at similar latitudes, roughly between 25° and 55° N, the scenes approximate what’s in the sky, although details of altitude and position will vary – especially visibility around dawn and dusk. Similarly, notes in this almanac that instruct you to look a specific time before sunrise or after sunset on a given calendar date are correct for observers in the United States and southern Canada. Star maps. The all-sky star maps illustrate the constellations as they appear at the times on your clock – that is, your local time – and even include the annual “Spring forward/fall back” changes of Daylight Saving Time. The dates of these clock changes, which are also noted in the almanac, follow the revised U.S. rules that went into effect in 2007. If your area does not recognize daylight time, then between March and November the star charts will be one hour ahead. Just make a note to look an hour earlier than indicated. Event listings. Some celestial events, such as conjunctions, lunar phases or eclipses, occur at specific times, whether or not North America is in darkness or pointed the right way to see them. For example, the most frequent event listings are conjunctions of the Moon with stars and planets, such as “Moon passes 1.5° south of Jupiter, 1 p.m. EST.” It may at first seem strange to include a conjunction that occurs in the afternoon, when Jupiter cannot be seen. What this is really saying: When you see the Moon in a dark sky on that date, Jupiter won’t be far away. Universal time. The traditional method for communicating the time of a celestial happening is to use Universal Time (UT), which for our purposes is identical to Coordinated Universal Time (UTC), the clock time on the meridian that runs through Greenwich, England (also known as Greenwich Mean Time). With the exception of eclipses and transits, the book gives UT times that are uncorrected for irregularities in Earth’s rotation, which astronomers estimate will not exceed 1.2 min by 2021. For lunar phases, oppositions, equinoxes and solstices, and Earth’s closest and farthest positions from the Sun, times are rounded to the nearest minute. Times for eclipses and transits, also rounded to the nearest minute, are based on predictions by astronomer Fred Espenak at NASA’s Goddard Space Flight Center. Less time-critical events are rounded to the nearest hour. For meteor showers, unless otherwise noted, the almanac gives the hour when Earth passes closest to the orbit of the shower’s parent body. The best viewing normally occurs during the hours after midnight closest to this time, although interference from the moon and specific shower behavior also come into play. While we’re most familiar with a 12-h clock, UT uses a 24-hr clock, where midnight, noon, and 6 p.m. become 0h, 12h, and 18h, respectively. To convert UT times to clock times at your location, you must add or subtract some number of hours, then switch from the 24-h UT clock to the 12-h format used by civil time. If the time shift passes midnight, the sky event may occur on a different calendar date than the one listed – and if you’re not mindful of that, you may miss the event.