Titan brighter at twilight than in daylight


Sketch showing the definition of phase angle

Muñoz, Antonio García, Panayotis Lavvas, and Robert A. West. “Titan brighter at twilight than in daylight.” Nature Astronomy 1, Article number: 0114 (2017) doi:10.1038/s41550-017-0114 (arXiv)

Investigating the overall brightness of planets (and moons) provides insights into their envelopes and energy budgets. Phase curves (a representation of the overall brightness versus the Sun–object–observer phase angle) for Titan have been published over a limited range of phase angles and spectral passbands. Such information has been key to the study of the stratification, microphysics and aggregate nature of Titan’s atmospheric haze and has complemented the spatially resolved observations showing that the haze scatters efficiently in the forward direction. Here, we present Cassini Imaging Science Subsystem whole-disk brightness measurements of Titan from ultraviolet to near-infrared wavelengths. The observations show that Titan’s twilight (loosely defined as the view at phase angles ≳150°) outshines its daylight at various wavelengths. From the match between measurements and models, we show that at even larger phase angles, the back-illuminated moon will appear much brighter than when fully illuminated. This behaviour is unique in our Solar System to Titan and is caused by its extended atmosphere and the efficient forward scattering of sunlight by its atmospheric haze. We infer a solar energy deposition rate (for a solar constant of 14.9 W m−2) of (2.84 ± 0.11) × 1014 W, consistent to within one to two standard deviations with Titan’s time-varying thermal emission from 2007 to 2013. We propose that a forward scattering signature may also occur at large phase angles in the brightness of exoplanets with extended hazy atmospheres and that this signature has a valuable diagnostic potential for atmospheric characterization.


Discotic Liquid Crystals with Graphene


Schematic illustration of columnar hexagonal arrangement of
discotic cores in 1-D semiconductor and charge migration.

Kumar, Manish, Ashwathanarayana Gowda, and Sandeep Kumar. “Discotic Liquid Crystals with Graphene: Supramolecular Self‐assembly to Applications.” Particle & Particle Systems Characterization (2017). doi:10.1002/ppsc.201700003 (sci-hub)

In past decades many breakthroughs have been witnessed in research on liquid crystals (LCs) and the application of LCs has spread. On another side graphene is considered as a rapidly rising star on the horizon of materials science, soft condensed matter physics and promising applications. Supramolecular chemistry of LCs and graphene together is described as “chemistry beyond the molecule”. A new class of 2D colloidal graphene oxide liquid crystalline material consisting discotic liquid crystallinity and their interactions with LCs present a platform for number of versatile properties and applications. This review focuses on discotic liquid crystalline (DLC) behavior of graphene oxide/reduced graphene oxide in various solvents, their characterization and application for energy storage, wet-spinning fibers, electro-optical devices, and displays etc. In the first part of this review, a brief introduction of discotic graphene oxide liquid crystals (GOLCs), their fundamental, synthesis process, supramolecular structures of graphene-DLC composites is highlighted. In the second part, some important physical studies and application of this largest polycyclic aromatic core of DLCs are discussed. Finally, an outlook on this emerging two dimensional material in liquid crystal field with relevant scientific application background is presented.

Creative mathematical tasks contribute to deeper learning in mathematics


Press Release

Mathias Norqvist

Mathias Norqvist

Working with creative mathematical tasks is important for pupils both to reflect on mathematics as well as for their subsequent test results. Being faced with creative tasks during exercise has evident effects on all pupils, both on weak and high performers. This according to studies at Umeå University in Sweden.
“The results of my dissertation show the importance for pupils to work with creative reasoning and not always get methods and rules presented in advance. This is something both publishers and teachers could take into account more often when designing mathematical tasks,” says Mathias Norqvist, doctoral student at the Department of Mathematics and Mathematical Statistics at Umeå University.
The studies show that pupils at upper secondary school who work with exercises designed to encourage creative mathematical reasoning more easily remember what they have learnt and, as a result, perform better.
“Contrary to common belief, it seems to be the low performing pupils who benefit most from practicing with creative tasks, in comparison to more imitative tasks where focus lies on how to use the given solutions,” says Mathias Norqvist.
There is a great risk that pupils who are presented one method, will use it without further reflection. Although, there are of course certain methods in mathematics that should be automated to relieve the pressure on the working memory, but it should not come at a cost to the understanding of the underlying mathematics. Since well-designed creative exercises can focus on central mathematical properties, they are important for all pupils since they force pupils to reflect on the mathematics and to base their reasoning on what they already know.
A total of about 300 upper secondary school pupils participated in the studies that formed the basis of the dissertation.

A quantum theory for thrones fans



Sydney University‘s delightful video in which academics predict who is going to win the Game of Thrones based on their disciplinary knowledge and understandings has had 62,500 Facebook likes, 900 YouTube hits and 10,000 Twitter impressions. The university has now uploaded, the full five-minute video of Michael Biercuk‘s quantum theory, which predicted a major event from the finale before it aired: ‘Tommin’s gotta die’. Biercuk has since been asked for further quantum physics theories, including how Bran can see into and interact with the past. The uni obviously harbours some hard core GoT fans. Back in 2014 it produced a video of Amy Johansen playing the GoT theme on the carillon, which was even watched by Davos Seaworth from the show.

via The Australian

Institutionalizing creationism


by Michael Baltzley on Science 10 Jun 2016, Vol. 352, Issue 6291, pp. 1285-1286 DOI: 10.1126/science.aaf7386

Biology faculty who teach evolution at U.S. colleges and universities often worry about the efforts of creationists to include the teaching of “intelligent design” in publicly funded high school biology courses. Now we also have cause to worry about students at publicly funded colleges and universities earning science credits for learning creationism.
The Western Interstate Commission for Higher Education (WICHE) is developing an Interstate Passport Initiative, funded in part by the U.S. Department of Education, which would streamline the learning outcomes for courses across institutions to facilitate the transfer of credits(1). Unfortunately, with the Passport Initiative, WICHE proposes making the creationist “teach the controversy” strategy as a standard part of college biology courses. In their document “Faculty handbook: Constructing your institution’s Passport block,” WICHE suggests that to demonstrate scientific literacy, students should “watch the Ken Hamm [sic]–Bill Nye evolution-creation debate and evaluate the scientific evidence and arguments used by the participants”(2).
This suggestion validates creationism as science by stating explicitly that both participants have scientific evidence. Middle school, high school, and college instructors who support creationism can point to the WICHE Passport Initiative as evidence that there is a scientific debate that includes creationism. The Answers in Genesis website has already promoted the debate as a way to get creationism into science classrooms(3).
If the goal of the curriculum is to help students use scientific evidence to debunk myths, the suggested class activity should be rephrased to read, “Watch the Ken Ham–Bill Nye evolution-creation debate and evaluate the arguments used by the participants.” However, even with better wording, by including the debate in a science class, WICHE is promoting the use of the Ham-Nye debate as an example of a scientific controversy. There are hundreds of genuine biological debates, both current and historical, that good educators can make interesting. WICHE should choose real examples of scientific debates and avoid advocating for creationism in science classrooms.
A student who takes general education courses at a WICHE Passport institution will soon be able to transfer the credits to any other Passport institution. The receiving institution cannot reject individual courses from approved institutions. Currently, WICHE lists 24 public institutions representing more than 150 campuses in seven U.S. states as participants in developing the Passport Initiative. WICHE plans to expand the Passport Initiative to six more states. As the Initiative grows, more and more public postsecondary institutions will be awarding science credits for courses that include creationism. To prevent the insertion of religion into science classrooms, scientists must speak out against the Passport Initiative until WICHE removes creationism from their suggested curriculum.

(1) Western Interstate Commission for Higher Education, The Interstate Passport.
(2) Interstate Passport, “Faculty handbook: Constructing your institution’s Passport block” (2016); p. 43 (pdf).
(3) Answers in Genesis, “Public schools and the Bill Nye/Ken Ham debate” (2014).