maravelias.info

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.

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

A short paper has been presented as a poster in the EPSC-DPS Joint Meeting 2019, held 15-20 September 2019 in Geneva, Switzerland. The data originate from a series of outreach activities performed by the Hellenic Amateur Astronomy Association, entitled “Introduction to Observational Astronomy“, which aimed to introduce interested individuals to the aspects of the observational techniques for scientifically useful observations, i.e. how amateur observations can help professionals and contribute to Astronomy in general (pro-am networking).

Evaluating introductory seminars on observational astronomy, using the Europlanet Evaluation Toolkit

Moutsouroufi, Konstantina; Maravelias, Grigoris; Marios Strikis, Iakovos; Kardasis, Emmanuel; Voutyras, Orfefs; Kountouris, Giorgos; Evangelopoulos, Athanasios; Aggelis, Konstantinos; Papadeas, Pierros; Schmidt, Tamara; Christou, Apostolos

During December 2018 – February 2019, the Hellenic Amateur Astronomy Association coordinated a series of seminars entitled “Introduction to Observational Astronomy”. The goal of this series was to introduce interested individuals to the aspects of the observational techniques for scientifically useful observations. Using the Europlanet Evaluation Toolkit we implemented a number of evaluation methods to receive feedback. The results show the participation of a mainly young audience ( 60% between 18-39), where females are represented more than equally ( 52%). Using the “pebbles in a jar” method a 94% of satisfied attendees was measured, while by using post-event surveys (questionnaires) the lectures were perceived as “(very) explicit” and “(very) interesting” (94%), fulfilling the attendees’ expectations (92%). It is important to note that 88% considers that their interest in Astronomy increased and is willing to get involved in observations.

NASA/ADS bibcode: 2019EPSC…13.1749M , poster: EPSC2019-poster

A recent paper, discussing radio observations to probe Jupiter’s atmosphere below its visible cloud layers, makes use of images obtained in the visible domain by amateurs (among who is Manos Kardasis).
They investigate ammonia gas from ~0.5 to ~10 bar (almost 100 km deep), and how it is distributed in a 3D “map”. Ammonia is driven from deep in the atmosphere to the upper layers and as it cools down it creates icy clouds, while the remaining air sinks down from regions without ammonia. The various radio bright/dark regions correlate well with features visible in the ir (e.g. 5μm hot spots) and visible (e.g. the Great Red Spot, white ovals), providing a link between these features and their driving mechanisms from within the atmosphere.

Imke de Pater, R. J. Sault, Bryan Butler, David DeBoer, Michael H. Wong
“Peering through Jupiter’s clouds with radio spectral imaging”
Science, 2016, 352, 1198
(links: Science, Berkeley News, The Gurdian)

The need for Professional-Amateur collaborations in studies of Jupiter and Saturn

Emmanuel Kardasis, John H. Rogers, Glenn Orton, Marc Delcroix, Apostolos Christou, Mike Foulkes, Padma Yanamandra-Fisher, Michel Jacquesson, Grigoris Maravelias

The observation of gaseous giant planets is of high scientific interest. Although they have been the targets of several spacecraft missions, there still remains a need for continuous ground-based observations. As their atmospheres present fast dynamic environments on various time scales, the availability of time at professional telescopes is neither uniform nor of sufficient duration to assess temporal changes. However, numerous amateurs with small telescopes (of 15-40 cm) and modern hardware and software equipment can monitor these changes daily (within the 360-900nm range). Amateurs are able to trace the structure and the evolution of atmospheric features, such as major planetary-scale disturbances, vortices, and storms. Their observations provide a continuous record and it is not uncommon to trigger professional observations in cases of important events, such as sudden onset of global changes, storms and celestial impacts. For example, the continuous amateur monitoring has led to the discovery of fireballs in Jupiter’s atmosphere, providing information not only on Jupiter’s gravitational influence but also on the properties and populations of the impactors. Photometric monitoring of stellar occultations by the planets can reveal spatial/temporal variability in their atmospheric structure. Therefore, co-ordination and communication between professionals and amateurs is important. We present examples of such collaborations that: (i) engage systematic multi-wavelength observations and databases, (ii) examine the variability of cloud features over timescales from days to decades, (iii) provide, by ground-based professional and amateur observations, the necessary spatial and temporal resolution of features that will be studied by the interplanetary mission Juno, (iv) investigate video observations of Jupiter to identify impacts of small objects, (v) carry out stellar-occultation campaigns.

arXiv:1503.07878

Mousis O., et al., 2013, arXiv:1305.3647
Instrumental Methods for Professional and Amateur Collaborations in Planetary Astronomy

This is a great collective work on various professional-amateur collaborations (written by both professionals and amateurs) regarding aspects of Planetary Astronomy, such as: terrestial planets (Mercury, Venus, Mars), gaseous planets (Jupiter, Saturn, Uranus, Poseidon), interstellar dust (meteoroids, meteors, fireballs, meteorites), Jupiter impacts, Lunar flashes, asteroids, comets, Kuiper belt objects and Centaurs, exoplanets.

I find it a really inspiring paper for both kinds! I hope that we will see more of these collaborations in the future, since the is a continuous advance in amateur contributions to Astronomy during the last decades.