明月幾時有？把酒問青天。不知天上宮闕，今夕是何年。
我欲乘風歸去，唯恐瓊樓玉宇，高處不勝寒。起舞弄清影，何似在人間。
轉朱閣，低綺戶，照無眠。不應有恨，何事長向別時圓？
人有悲歡離合，月有陰晴圓缺，此事古難全。但願人長久，千里共嬋娟。
~ 蘇軾．〈水調歌頭〉
語譯：月亮是從何時開始有的？我舉起酒杯，仰問上天。不知仙人住的天宮，今夜是哪一年的中秋了。我也想乘風歸去天上的仙府，卻又害怕會抵受不住高處的冷寒。我還是就待在原處，隨著月光年體沉醉起舞吧。
月光移照朱紅華美的樓閣，低低地照進雕花的門窗裡去，照著無法入眠的愁人。月亮對人間不該有什麼怨恨吧，為什麼總是在人們離別、孤獨的時候特別亮、特別圓？人生本來就聚聚散散，月亮從來就是圓圓缺缺，想要永恆的相聚圓滿，自古就不可得。雖然相隔分離，但只要人事平安，依舊可以跨過千里青天，共享美麗的月光。
Apollo Landing Sites
Apollo 11 Extravehicular Activity (EVA)
On July 20, 1969, man landed on the Moon and took steps that would inspire future generations and open the heavens to exploration. After spending four days in a spacecraft on the way to the lunar surface, astronaut Neil Armstrong famously announced, “The Eagle has landed.” Shortly afterwards, Armstrong and Edwin “Buzz” Aldrin descended from the Lunar Module and began humankind’s exploration of the moon’s surface.
Armstrong and Aldrin landed in a dark patch of the lunar surface called the Sea of Tranquility, one of the Moon’s maria. These dark regions, which can be seen with the naked eye from Earth, were named maria by early explorers after the Latin word for seas. (The singular form is mare, pronounced “ma-rei”.) The relatively smooth surface of the maria allowed for good radio communication with the Earth and provided a nice, flat site for the first lunar landing.
Apollo 12 Extravehicular Activity (EVA)
On November 19, 1969, the crew of Apollo 12 executed a pinpoint landing on the lunar surface, setting their spacecraft down a few hundred meters from the rim of Surveyor Crater. The main goal of the mission was to collect pieces of the Surveyor III spacecraft, which had landed in this particular crater 31 months earlier. Pinpoint landing was critical to this goal, and astronauts Pete Conrad and Al Bean performed it flawlessly.
Dick Gordon, the command module pilot, joined Conrad and Bean on the all-Navy crew of Apollo 12. With the weight of making the first historical landing covered by the Apollo 11 crew before them, the Apollo 12 astronauts felt free to joke and banter as they accomplished their tasks.
Pinpoint landing was but one of many improvements made in this mission over its predecessor. The astronauts explored the lunar surface on two extravehicular activity (EVA) periods rather than only one, and during these EVAs the Apollo 12 astronauts deployed several more scientific experiments, gathered more lunar rock samples, and ventured further from the Lunar Module, giving scientists a wealth of new information about the landing site and the Moon in general.
Apollo 14 Extravehicular Activity (EVA)
On February 5, 1971, the crew of Apollo 14 touched down on the lunar surface in the Fra Mauro formation near Cone Crater. It was the second attempt to land at this site. Originally, Apollo 13 had been slated to land at Fra Mauro and Apollo 14 was to explore a site near Littrow Crater. The Apollo 13 accident had altered these plans.
Fra Mauro was a site of extreme interest for lunar scientists. It sits on the edge of the lava-filled Imbrium Basin, which is the largest lunar mare associated with an ancient impact event. A basin the size of the Mare Imbrium could only be created by an impact of truly gigantic proportions—such an impact would have been a key event in lunar history. The hilly Fra Mauro formation appears to have been formed by ejecta from this enormous collision. If this interpretation was correct, scientists would be able to date the formation of the Imbrium Basin by collecting samples of the Fra Mauro bedrock.
Rock samples from Fra Mauro were also likely to refine our understanding of the early solar system, a time when the Earth, Moon, and other planets were still forming. On Earth, the dynamic environment of plate tectonics, volcanism, and erosion have long since eradicated this early geologic history, but ancient rocks on the moon have been well preserved. Apollo 14 was an opportunity for geologists to go hunting for some of the oldest rocks ever dated.
The Apollo 14 crew was thrilled to be on the Moon. The occasion was particularly significant for the commander, Alan Shepard, who had been the first American in space but had then been grounded after his brief flight due to an inner-ear disorder. After a decade on the ground and corrective surgery he was given command of Apollo 14, joining Stuart Roosa and Edgar Mitchell on the mission. At Fra Mauro, Shepard and Mitchell deployed several scientific experiments and made a three kilometer geological traverse on foot near Cone Crater. This traverse showed that astronauts were physically capable of traveling long distances on the lunar surface, thereby paving the way for the longer and more complicated missions to come.
Apollo 15 Extravehicular Activity (EVA)
Apollo 15, which touched down near Hadley Rille on July 8, 1971, was a large leap forward for the Apollo program. The earlier missions were largely engineering challenges designed to achieve the goal of getting men safely to and from the Moon. Having shown that this could be done, NASA was ready to move on to missions that featured more extensive scientific exploration and experimentation. Apollo 15 was the first of the so-called “J-missions”, which were characterized by longer extravehicular activity (EVA) periods, landing sites with complex geology, and an increased number of scientific experiments.
Unlike previous Apollo landing sites, which had each contained a single geological point of interest, the Apollo 15 site was chosen because it contained a variety of interesting destinations to visit and understand. There was Hadley Rille, a sinuous lava channel winding 100-km through the lunar surface; the Apennine Front, a sizable mountain range overlooking a mare plain; and Hadley Delta, a high mountain peak.
Apollo 15 astronauts shattered the record for extravehicular activity (EVA) time. By logging 18 and one half hours outside the Lunar Module in three EVAs, the astronauts nearly doubled the traverse time of the Apollo 14 mission. The scientific payload carried and the number of rock samples returned were also nearly double those of Apollo 14.
Apollo 15 also featured the debut of the Lunar Roving Vehicle (LRV). This four-wheel-drive dune buggy was a great step forwards in surface mobility—it allowed the astronauts to travel much farther from the Lunar Module and carry many more tools and samples. With the LRV, the astronauts could drive several kilometers to visit the diverse geological objectives at the landing site.
Apollo 16 Extravehicular Activity (EVA)
As the time approached for the Apollo 16 Lunar Module to descend from lunar orbit to the Moon’s surface, Ken Mattingly, the Command Service Module pilot, found that the backup gimbals (mechanical devices that allow rotation in multiple axes) in the Command Service Module were faulty. These gimbals controlled the direction that the Command Service Module rockets fired, and without them, the crew would be forced to use the Lunar Module engines to return to Earth. Mission rules dictated that, in this scenario, the lunar landing would be canceled. However, after six long hours of troubleshooting and analysis by engineers in Houston, Mission Control made the call that the margins for safety were just barely adequate and they gave Apollo 16 the “Go” for lunar landing.
On April 21, 1972, exploration of the lunar surface continued as Apollo 16 touched down in the Descartes highlands. Unlike previous landing sites, which had contained clues about the historical period during which the maria (the dark, lava filled plains on the Moon’s surface) had formed, Descartes was chosen as a site to study the origins of the lunar highlands.
Of the potential sites in the lunar highlands that had been considered, Descartes was chosen because it appeared to be the an area with much volcanic activity. There was consensus among geologists at the time that the landing site contained typical examples of viscous lava flows that had piled up to create the hilly formations in the area, and some scientists had even gone so far as to chart various flow fronts and cinder cones. Accordingly, Charles Duke and John Young had been thoroughly trained in terrestrial volcanic analogs. Therefore, it was quite a shock when, soon after Apollo 16 landed, Duke and Young reported that they could see no evidence of volcanic rocks at the landing site.
Duke and Young were able to build on the experience of prior Apollo astronauts to help them complete the longest lunar extravehicular activity (EVA) period yet. With the help of the Lunar Roving Vehicle, the astronauts covered several kilometers of highland territory and brought back the second-largest collection of samples of all the missions, including the largest rock taken from the Moon.
Apollo 17 Extravehicular Activity (EVA)
On December 11, 1972, astronauts Harrison H. (Jack) Schmitt and Eugene Cernan stepped onto the lunar surface as part of the Apollo program's last mission to the Moon. (Ronald Evans, the other member of the crew, stayed in lunar orbit as the Command Module pilot.) In a few short years, humans had gone from achieving President Kennedy’s goal of landing a man on the Moon to supporting a prolonged three-day stay on the lunar surface during which the astronauts carried out a complex geology field campaign.
The Apollo 17 mission was an exciting and challenging end to the Apollo program. Schmitt and Cernan set down in the Taurus-Littrow valley; a site with tremendous geological variety. It contained dark, potentially volcanic craters surrounded by soaring mountains that were formed when large units of bedrock were displaced during the catastrophic meteor impact that formed the Serenitatis Basin. Were the dark craters evidence of recent volcanic activity on the moon? How old were the massifs that surrounded the valley? The astronauts would sample each of these features to answer these questions and hopefully piece together the valley’s complicated history.
Apollo 17 set many records in the Apollo program. This mission’s astronauts brought back the largest bulk of lunar samples, explored the most territory, and spent the longest time outside the Lunar Module on extravehicular activities (EVAs). This was also the only mission on which a professional geologist, Schmitt, was able to explore the lunar surface as a field geologist, thereby greatly increasing the chance for “opportunistic science” to take place.
*Note: Apollo 13 was supposed to land in the Fra Mauro area. An explosion on board forced Apollo 13 to circle the moon without landing. The Fra Mauro site was reassigned to Apollo 14.
Blue Moons
There are also months with two full moons. The second full moon in a month is known as a blue Moon. Because this happens fairly infrequently, it has resulted in the expression "once in a blue moon."
Months without a full moon
There are months in which no full moons occur. For example, there was a full moon at 18:25 universal time on Feb. 28, 1991. This means there was no February full moon in east Asia and the Pacific, where it was already March. Years in which February lacked a full moon are 1809, 1847, 1866, 1885, 1915, 1934, 1961, 1999, 2018, 2037, 2067, 2094 (Meeus 1995, Odenwald)
Moon rise times
The New Moon always rises at sunrise.
The first quarter Moon rises at noon.
The Full Moon rises at sunset.
The last quarter Moon rises at midnight.
Moonrise takes place about 50 minutes later each day than the day before.
