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Maya conflict left many images. With a few exceptions, however, they reveal limited numbers of victors and captives In contrast, glyphic accounts point to broader convulsions, and the challenge remains of linking such conflicts to the infrastructure of concerted attack and defense. Lidar, a technology using laser pulses to record and model surfaces, does so with aplomb. By now, most Mayanists accept that, in the late 4th century A.D., Classic Maya kingdoms became entangled with the distant polity of Teotihuacan, Mexico. Tikal refers to that encounter in precise detail, identifying an enigmatic, victorious belligerent, Sihyaj K’ahk’, and possible ruptures in the local dynasty. To unexpected extent, lidar shows that the western entry to Tikal bristled with numerous citadels, surveillance platforms, moats with protected settlement, and ramps for rapid ascent and descent on high ridges and hilltops. Current evidence places these features in the general time of Sihyaj K’ahk’, underscoring that the threat and actuality of violence enmeshed regions, at systemic scale. 

Lowland Maya civilization flourished in the tropical region of the Yucatan peninsula and environs for more than 2500 years (~1000 BCE to 1500 CE). Known for its sophistication in writing, art, architecture, astronomy, and mathematics, Maya civilization still poses questions about the nature of its cities and surrounding populations because of its location in an inaccessible forest. In 2016, an aerial lidar survey across 2144 square kilometers of northern Guatemala mapped natural terrain and archaeological features over several distinct areas. We present results from these data, revealing interconnected urban settlement and landscapes with extensive infrastructural development. Studied through a joint international effort of interdisciplinary teams sharing protocols, this lidar survey compels a reevaluation of Maya demography, agriculture, and political economy and suggests future avenues of field research. 

The citizen Continental-America Telescopic Eclipse (CATE) Experiment was a new type of citizen science experiment designed to capture a time sequence of white-light coronal observations during totality from 17:16 to 18:48 UT on 2017 August 21. Using identical instruments the CATE group imaged the inner corona from 1 to 2.1 RSun with 1.″43 pixels at a cadence of 2.1 s. A slow coronal mass ejection (CME) started on the SW limb of the Sun before the total eclipse began. An analysis of CATE data from 17:22 to 17:39 UT maps the spatial distribution of coronal flow velocities from about 1.2 to 2.1 RSun, and shows the CME material accelerates from about 0 to 200 km s⁻¹across this part of the corona. This CME is observed by LASCO C2 at 3.1–13 RSun with a constant speed of 254 km s⁻¹. The CATE and LASCO observations are not fit by either constant acceleration nor spatially uniform velocity change, and so the CME acceleration mechanism must produce variable acceleration in this region of the corona.