Waxing Gibbous Moon Shows Tycho Crater in Bright Southern Highlands

Summary: From July 14 to July 18, 2016, the waxing gibbous moon shows Tycho crater as a sharply defined depression in the bright Southern Highlands.

Tycho crater (bottom center), with prominent central peak, punctuates Southern Highlands; mosaic of moon compiled for NASA’s APOD (Astronomy Picture of the Day), Sept. 3, 1995, from images captured by spacecraft Clementine in 1994: Clementine/BMDO/NRL/LLNL, Public Domain, via NASA Astronomy Picture of the Day (APOD)

From Thursday, July 14, to Monday, July 18, 2016, the waxing gibbous moon, surging from 73 to 98 percent visibility, shows Tycho crater as a sharply defined depression in the bright, densely cratered Southern Highlands.

Moonrise times for the five days span late afternoon to early evening for Eastern Daylight Time zoners. The waxing gibbous moon rises Thursday, July 14, at 3:51 p.m. (19:51 Coordinated Universal Time); Friday, July 15, at 4:46 p.m. (20:46 UTC); Saturday, July 16, at 5:41 p.m. (21:41 UTC); Sunday, July 17, at 6:34 p.m. (22:34 UTC); Monday, July 18, at 7:24 p.m. (23:24 UTC).

Moonset times happen in the early morning hours. The waxing gibbous moon sets Friday, July 15, at 2:34 a.m. (06:34 UTC); Saturday, July 16, at 3:13 a.m. (07:13 UTC); Sunday, July 17, at 3:58 a.m. (07:58 UTC); Monday, July 18, at 4:48 a.m. (08:48 UTC).

Tycho crater is sufficiently conspicuous for visibility to unaided eyes. Binoculars and telescopes, obviously, clarify details of the lunar impact crater, such as its vast ray system and darkened rim.

The coordinates for the prominent crater’s center are minus 43.3 degrees south latitude, 11.22 degrees east longitude, according to The International Astronomical Union's (IAU) Gazetter of Planetary Nomenclature. The crater’s diameter measures 86 kilometers (53.43 miles). Tycho plunges to a depth of 4.8 kilometers (2.98 miles).

Tycho’s east side features a relatively smooth floor. Roughness characterizes the floor from the central peak to the west wall. Currently astronomers credit impact-melted debris with both roughly and smoothly veneering the floor’s original surface.

A central peak complex measures a southeast to northwest width of about 15 kilometers (9.32 miles). The crater’s central peak rises to a height of 2.25 kilometers (1.39 miles).

Variably-sized clasts, or fragments, clutter the slopes of the central peak complex. Distinctive outcrops or rebounds of crust rocks are suspected origins of the peak’s clastic rocks.

Tycho’s ray system sprawls extensively over approximately 560,000 square kilometers (216,217 square miles) of the lunar surface. Tycho’s bright rays stretch to the east, northwest and south, but they do not streak westward.

Sky & Telescope columnist Charles A. Wood, a planetary geologist, finds that the directional rays, along with greater eastward widths of the crater’s surrounding grey white nimbus, suggest Tycho’s formation from an oblique impact. An oblique angle, at less than 45 degrees, would predominantly direct ray materials downrange. Tycho’s impactor, with a probable width of 8 to 10 kilometers (4.97 to 6.21 miles), hugged the moon’s western horizon as it hurtled toward its destination.

Glassy impact melt deposits distinguish the crater’s rim with a dark ring. Tycho’s youthfulness accounts for the crater’s distinctive, dark ring. Continual barrages by small impacts over a billion years will transform the darkened rim by pulverizing rim deposits and blending them with surrounding rocks.

Tycho’s youthfulness garners the distinctive crater’s status as the youngest large crater on the near side of the moon. Radiometric dating of probably Tycho-originated impact melt glass at the Apollo 17 landing site yields a formation date of 108 million years. Contrastingly, many large lunar craters are aged at 3.9 billion years.

Giovanni Battista Riccioli (April 17, 1598-June 25, 1671), a Jesuit astronomer who studiously examined the moon, named Tycho crater after Danish astronomer and nobleman Tycho Brahe (Dec. 14, 1546-Oct. 24, 1601). Comprehensive tables of accurate astronomical and planetary observations, compiled from his naked eye method, constitute Brahe’s vibrant legacy to astronomy.

The takeaway for July’s waxing gibbous moon is the easy, aided or unaided viewing of showy Tycho crater's bright stretches across the lunar surface in the bright Southern Highlands.

sunrise view of Tycho Central Peak, with 100-meter (about 328-foot) boulder at summit; image captured June 10, 2011, by LRO (Lunar Reconnaissance Orbiter) NACs (Narrow Angle Cameras): LRO Mission, Public Domain, via NASA

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Tycho crater (bottom center) in bright, densely cratered Southern Highlands; mosaic of moon compiled for NASA’s APOD (Astronomy Picture of the Day), Sept. 3, 1995, from images captured by spacecraft Clementine in 1994: Clementine/BMDO/NRL/LLNL, Public Domain, via NASA Astronomy Picture of the Day (APOD) @ http://apod.nasa.gov/apod/ap950903.html

sunrise view of Tycho Central Peak, with 100-meter (about 328-foot) boulder at summit; image captured June 10, 2011, by LRO (Lunar Reconnaissance Orbiter) NACs (Narrow Angle Cameras): LRO Mission, Public Domain, via NASA @ https://www.nasa.gov/content/lunar-reconnaissance-orbiters-view-of-tycho-central-peak

For further information:

Consolmagno, Guy; Dan M. Davis. Turn Left at Orion: Hundreds of Night Sky Objects to See in a Home Telescope -- and How to Find them. Fourth edition. New York NY: Cambridge University Press, 2011.

Dundas, Colin M.; Alfred S. McEwen. “Rays and Secondary Craters of Tycho.” Icarus, vol. 186, issue 1 (January 2007): 31-40.
Available via Science Direct @ http://www.sciencedirect.com/science/article/pii/S0019103506002788

“The Floor of Tycho Crater.” NASA > Missions > LRO (Lunar Reconnassiance Orbiter) > Multimedia. Jan. 14, 2010.
Available @ http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100114-tycho.html

Fuller, David. "Moon Maps." Eyes on the Sky > Moon.
Available @ http://www.eyesonthesky.com/Moon.aspx

International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). “Tycho.” USGS Astrogeology Science Center > Gazetter of Planetary Nomenclature. Last updated Oct. 18, 2010.
Available @ https://planetarynames.wr.usgs.gov/Feature/6163

Loff, Sarah. “Lunar Reconnaissance Orbiter's View of Tycho Central Peak.” NASA > LRO (Lunar Reconnaissance Orbiter). June 18, 2014.
Available @ https://www.nasa.gov/content/lunar-reconnaissance-orbiters-view-of-tycho-central-peak

LRO_LROC. “LROC Explores Tycho Central Peak.” YouTube. June 29, 2011.
Available @ https://www.youtube.com/watch?v=361YcacQZjg

Marriner, Derdriu. "Waxing Gibbous Moon: Fourth of Eight Phases in Monthly Lunar Cycle." Earth and Space News. Friday, Feb. 27, 2015.
Available @ https://earth-and-space-news.blogspot.com/2015/02/waxing-gibbous-moon-fourth-of-eight.html

"Moonrise, Moonset, and Phase Calendar for Washington DC, July 2016." Time And Date > Sun & Moon > Moonrise and Moonset.
Available @ https://www.timeanddate.com/moon/usa/washington-dc?month=7&year=2016

Robinson, Mark. “Tycho Central Peak Spectacular!” Arizona State University School of Earth and Space Exploration Lunar Reconnaissance Orbiter Camera (LROC) Science Operations Center (SOC) > Posts. June 29, 2011.
Available @ http://lroc.sese.asu.edu/posts/384

Scagell, Robin. Firefly Complete Guide to Stargazing. Buffalo NY: Firefly Books Inc.; Richmond Hill, Canada: Firefly Books Ltd.; London, England: Philip's, 2015.

"Sunrise View of Tycho Crater's Peak." NASA Home > Missions > LRO > News & Media Resources. June 30, 2011.
Available @ https://www.nasa.gov/mission_pages/LRO/news/lro-tycho.html

Webb, Brian. “Coordinated Universal Time (UTC).” Space Archive. May 27, 2016.
Available @ http://www.spacearchive.info/utc.htm Wood, Charles A. “Tycho: The Metropolitan Crater of the Moon.” Sky & Telescope > Observing > Celestial Objects to Watch. Aug. 1, 2006.
Available @ http://www.skyandtelescope.com/observing/celestial-objects-to-watch/tycho-the-metropolitan-crater-of-the-moon/