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New Paper: Amateur Observers Witness the Return of Venus’ Cloud Discontinuity

The following paper is the result of a tedious task that my good friend Manos Kardasis undertook over the last two+ years. He noticed the presence of this (relatively newly discovered) feature in Venus and collected images from amateur observers worldwide to study in detail the discontinuity and constrain some of its properties by comparison with data from JAXA’s Akatsuki.

The importance of this work is twofold: a. it shows the high potential of observations with small telescopes to perform scientific studies of quality, and b. it promotes and encourage encourage amateur observers to perform and increase the observations of Venus.

I am really happy with this paper as it is a very well-deserved outcome of the work and effort that Manos put into this (fighting and joggling with many other things at the same time) and it showcases how a professional-amateur collaboration can succeed. Well done Manos!

Amateur Observers Witness the Return of Venus’ Cloud Discontinuity

Kardasis E., Peralta J., Maravelias G., Imai M., Wesley A., Olivetti T., Naryzhniy Y., Morrone L., Gallardo A., Calapai G., Camarena J., Casquinha P., Kananovich D., MacNeill N., Viladrich C., Takoudi A.

Firstly identified in images from JAXA’s orbiter Akatsuki, the cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. Interpreted as a new type of Kelvin wave, this disruption is associated to dramatic changes in the clouds’ opacity and distribution of aerosols, and it may constitute a critical piece for our understanding of the thermal balance and atmospheric circulation of Venus. Here, we report its reappearance on the dayside middle clouds four years after its last detection with Akatsuki/IR1, and for the first time, we characterize its main properties using exclusively near-infrared images from amateur observations. In agreement with previous reports, the discontinuity exhibited temporal variations in its zonal speed, orientation, length, and its effect over the clouds’ albedo during the 2019/2020 eastern elongation. Finally, a comparison with simultaneous observations by Akatsuki UVI and LIR confirmed that the discontinuity is not visible on the upper clouds’ albedo or thermal emission, while zonal speeds are slower than winds at the clouds’ top and faster than at the middle clouds, evidencing that this Kelvin wave might be transporting momentum up to upper clouds.

Figure 1: Observations of cloud discontinuities, observed in the 2019/2020 eastern elongation of Venus, showing different morphologies.

arXiv: 2202.12601
Journal: Atmosphere 2022, 13(2), 348

Planets around A-type stars

For an unknown reason I found this footnote from Menu et al. 2015 (A&A, 581A, 107) very interesting:

It is interesting to note that several of the few directly imaged planetary companions are found around A-type stars, which are descendants of Herbig Ae/Be stars. Examples of A-type exoplanet host stars are HR 8799 (e.g., Marois et al. 2008), HD 95086 (e.g., Rameau et al. 2013), κ And (e.g., Carson et al. 2013), β Pic (e.g., Lagrange et al. 2010), and HD 100546 (e.g., Quanz et al. 2013).

First results on the Pluto system by New Horizons

The first scientific results regarding the Pluto system as observed from New Horizons have been published in Science [1]. It is impressive to see direct images and maps of such distant worlds.

Maps of Pluto (A) and Charon (B) with informal feature names (see Fig. 2 and text in Stern et al. 2015, for more details).

Maps of Pluto (A) and Charon (B) with
informal feature
names (see Fig. 2 and text in Stern et al. 2015, for more details).

More remarkable is the complex geology and geomorphology which characterize both Pluto and Charon. Pluto is by far a non-dead planet as resurfacing is indicative is some areas, which is puzzling as there are no obvious energy sources for such activity. Moreover, water ice may be the basis for the formation of high mountains (up to 2-3 km) as N2, CO, and CH4 cannot form such structures.

Pluto’s atmosphere, as measured by solar UV absorption, is characterized by N2 at ~1670km, CH4 below ~960km, C2H4 at ~300km, haze below ~150km, and C2H2 at ~50km. Additionally, UV and high-energy radiation interact with the these particles giving raise to tholins (a form of organic molecules).

The other two moons to be observed, Nix and Hydra, displayed high albedo, probably due to cleaner (compared to what is found in Charon) water ice – another puzzling issue since there is a number of processes that could darken their surfaces (like transfer of darker material from Charon or Kuiper meteorites).

More results are forthcoming, since there are data (e.g. UV spectra) that have not been downlinked from the satellite yet.

[1] Stern et al., 2015, Science, vol. 350, 292,
or arXiv:1510.07704

Planetary imaging from Skinakas telescope

In late August 2012 we (me and Manos Kardasis) tested the video capture method for planetary imaging using the 1.29m Skinakas‘ telescope. Although not aware of what problems to expect we finally didn’t encounter any (as Manos had been really working on this with great care and caution) but for the weather and seeing.
So, the test proved successful and all that is needed next time it good seeing.
Below you can see images of the equipment used and the results on Jupiter, Uranus and Neptune.
(Jupiter observations were also forwarded to Planetary Virtual Observatory & Laboratory / Jupiter section.)

Skinakas' 1.29m equipped for planetary imaging


Equipment: DMK/DBK video camera + barlow 2x (if needed) + filter wheel (L,R,G,B,Ch4,IR,UV) + eyepiece with flip mirror