The planet Venus has been especially prominent in the evening sky these past few weeks, joining Jupiter and a waxing Moon in a sparkling, slow-motion dance of celestial bodies. On clear nights at the summit of Kīlauea, this spectacle has complemented the other-worldly glow reflected by clouds above the lava lake in Halema‘uma‘u Crater.
Volcano Watch — Is Earth’s Neighbor Volcanically Active?
Scientists who study Venus have demonstrated convincingly that the planet's surface has been shaped by active tectonics and volcanic activity for much of its history. Using radar to penetrate the dense Venusian atmosphere, spacecraft flown since the 1980s have revealed an array of volcanic landforms such as lava flows, cones, massive shields, steep-sided lava domes, and large rift zones. But no strong evidence of ongoing volcanic activity was found—until recently.
In May 2015, a team of scientists from Germany, Russia, Ukraine, and the United States published evidence that Venus may, in fact, be a location of modern volcanism. If true, Venus would join Earth and two of Jupiter's moons, Io and Europa, in the growing club of celestial bodies in our Solar System known to host active volcanism.
The evidence comes from data acquired by the European Space Agency's Venus Express mission. Examining new imagery, the team detected regions of unusually high temperatures—some reaching more than 400 degrees Celsius (752 degrees Fahrenheit) above the planet's already toasty average surface temperature of about 800 degrees Celsius (1472 degrees Fahrenheit). The high temperature areas extended over regions ranging from 1 square kilometer (250 acres) to more than 200 square kilometers (77 square miles).
Remarkably, these high temperatures, recorded over several days of repeated observations mysteriously disappeared in subsequent satellite passes. Based on a careful analysis of the data, mission scientists concluded that the spikes in temperature are best explained as transient heat from active lava flows. We see similar behavior at Kīlauea Volcano, where active lava flows are seen as 'hot spots' in images from orbiting satellites. Days later, when lava flows have cooled, these spots fade away.
The areas of unusually high temperature on Venus occurred in a large rift zone structure—similar to a gigantic Kīlauea East Rift Zone. The Venusian rift, called Ganiki Chasma, is located near two prominent volcanoes with the delightful names of Ozza Mons and Maat Mons. This striking geologic feature was identified as a young volcanic landform in data collected by the Soviet Venera missions of the 1980s and the U.S. Magellan mission in the 1990s.
Despite the excitement of this new evidence, there were already earlier hints of modern volcanism on Venus. In 2010, studies of the radar properties of one lava flow complex suggested increased subsurface temperatures consistent with cooling lavas. Also, in the late 1980s, and again in 2012, scientists reported temporary increases in sulfur dioxide in Venus' upper atmosphere (Venusian vog!), another clue that volcanoes may have been recently active.
Venus has long been considered an analog for Earth. So, confirming ongoing volcanism there could have exciting implications for better understanding the evolution of our own planet.
Imagining actively erupting volcanoes on Earth's neighbor is exciting to many volcanologists who began their professional careers looking at volcanic features on the Moon and Mars. The challenge to confirm or deny the case for active volcanism on Venus and other planetary bodies will certainly inspire a whole new generation of planetary volcanologists.
Volcano Activity Update
Kīlauea's summit lava lake level, which fluctuates in response to summit inflation and deflation, remained fairly steady at 45 m (148 ft) below the vent rim for much of the past week, but dropped to 47 m (155 ft) on July 1, where it remained as of July 2.
Kīlauea's East Rift Zone lava flow continues to feed widespread breakouts northeast of Pu‘u ‘Ō‘ō. Active flows are slowly covering and widening the flow field, but remain within about 8 km (5 mi) of Pu‘u ‘Ō‘ō.
There were two earthquakes reported felt on the Island of Hawai‘i during the past week. On Saturday June 27, 2015, at 10:10 p.m., HST, a magnitude-5.2 earthquake occurred 11 km (7 mi) southeast of Kīlauea Summit at a depth of 8.5 km (5.3 mi), and at 10:54 p.m., a magnitude-3.2 earthquake occurred 13 km (8.5 mi) southeast of Kīlauea Summit at a depth of 8.8 km (5.5 mi).