Tag Archives: Albedo

TACNY Junior Cafe Scientifique: “A Tale Of Ice And Fire: What Bugs And Mud Can Teach Us About The Past”

Saturday, January 18, 2020; 9:30 – 11:00am

Milton J Rubenstein Museum of Science & Technology – Syracuse, NY

Please RSVP to jrcafe@tacny.org

Speaker: Melissa L. Chipman, PhD; Assistant Professor, Department of Earth Sciences, Syracuse University

Talk Overview: The Arctic is one of the most rapidly changing regions on Earth. Arctic biomes are underlain by permafrost soils, some of which contain large deposits of ice left over from ice sheets that retreated thousands of years ago. As temperatures continue to increase the Arctic, these large ice deposits thaw and form dramatic landslides and thaw slumps, which move massive amounts of sediment around the landscape. In addition, warming temperatures facilitate fires in areas that have not burned for thousands of years. Fires impact soil properties such as albedo, vegetation, and soil temperatures, which may lead to enhanced thaw of these ice deposits. Thus, Arctic change is really a story of ice and fire and how these aspects of the system interact. One of the best ways to anticipate how future warming will impact these processes is investigate how Arctic systems responded to temperature change in the past. Lakes record changes that happen on the surrounding landscape because fires produce charcoal that gets deposited in waterbodies, thaw slumps transfer old glacial sediment into lake basins, and insects that are sensitive to temperatures live in many Arctic lakes. We will explore ways to use these signals in lake-sediment cores to investigate the past and uncover how Arctic ecosystems have responded to changing climate over thousands of years. 

Biography: Dr. Chipman received her bachelor’s degree in Environmental Geosciences from Concord University in West Virginia. She received a M.S in Geology. and a Ph.D. in Ecology from the University of Illinois in Urbana-Champaign. She was also a postdoctoral research fellow at Northwestern University and joined the faculty in Earth Sciences at Syracuse University in January 2019. Dr. Chipman has extensive experience investigating Arctic change and has participated in six remote field campaigns in boreal and tundra areas of Alaska and Greenland. She is a National Geographic Explorer and currently has a grant from the National Science Foundation to continue her research into fire and ice disturbance in the Arctic. She has also worked on projects funded by the Environmental Protection Agency and was one of the last EPA STAR fellows. Dr. Chipman was a first-generation college student and the first in her family to attend and graduate high school, and is committed to promoting opportunities for first-generation and unrepresented students in science. She mentored several undergraduate students through independent research projects, and is currently advising two graduate students in her new Arctic Paleoecology and Paleoclimate lab group at Syracuse University.

TACNY Junior Cafe Scientifique

TACNY Junior Cafe Scientifique, a program for middle-school students founded in 2005, features discussions about topics in the fields of science, technology, engineering and mathematics in an informal atmosphere and seeks to encourage students to consider careers in these areas. Students must be accompanied by an adult and can explore the MOST at no cost after the event.

Technology Alliance of Central New York

Founded in 1903 as the Technology Club of Syracuse, the nonprofit Technology Alliance of Central New York’s mission is to facilitate community awareness, appreciation, and education of technology; and to collaborate with like-minded organizations across Central New York.

For more information about TACNY, visit www.tacny.org.

NASA Space Place – On The Brightness Of Venus

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in July, 2015.

By Dr. Ethan Siegel

2013february2_spaceplaceThroughout the past few months, Venus and Jupiter have been consistently the brightest two objects visible in the night sky (besides the moon) appearing in the west shortly after sunset. Jupiter is the largest and most massive planet in the solar system, yet Venus is the planet that comes closest to our world. On June 30th, Venus and Jupiter made their closest approach to one another as seen from Earth—a conjunction—coming within just 0.4° of one another, making this the closest conjunction of these two worlds in over 2,000 years.

And yet throughout all this time, and especially notable near its closest approach, Venus far outshines Jupiter by 2.7 astronomical magnitudes, or a factor of 12 in apparent brightness. You might initially think that Venus’s proximity to Earth would explain this, as a cursory check would seem to show. On June 30th Venus was 0.5 astronomical units (AU) away from Earth, while Jupiter was six AU away. This appears to be exactly the factor of 12 that you need.

Only this doesn’t explain things at all! Brightness falls off as the inverse square of the distance, meaning that if all things were equal, Venus ought to seem not 12 but 144 times brighter than Jupiter. There are three factors in play that set things back on the right path: size, albedo, and illumination. Jupiter is 11.6 times the diameter of Venus, meaning that despite the great difference in distance, the two worlds spanned almost exactly the same angular diameter in the sky on the date of the conjunction. Moreover, while Venus is covered in thick, sulfuric acid clouds, Jupiter is a reflective, cloudy world, too. All told, Venus possesses only a somewhat greater visual geometric albedo (or amount of reflected visible light) than Jupiter: 67 percent and 52 percent, respectively. Finally, while Venus and Jupiter both reflect sunlight toward Earth, Jupiter is always in the full (or almost full) phase, while Venus (on June 30th) appeared as a thick crescent.

All told, it’s a combination of these four factors—distance, size, albedo, and the phase-determined illuminated area—that determine how bright a planet appears to us, and all four need to be taken into account to explain our observations.

Don’t fret if you missed the Venus-Jupiter conjunction; three more big, bright, close ones are coming up later this year in the eastern pre-dawn sky: Mars-Jupiter on October 17, Venus-Jupiter on October 26, and Venus-Mars on November 3.

Keep watching the skies, and enjoy the spectacular dance of the planets!


Caption: Image credit: E. Siegel, using the free software Stellarium (L); Wikimedia Commons user TimothyBoocock, under a c.c.-share alike 3.0 license (R). The June 30th conjunction (L) saw Venus and Jupiter pass within 0.4° of one another, yet Venus always appears much brighter (R), as it did in this image from an earlier conjunction.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/