Readers ask about life on Venus and high-energy cosmic rays

Venusian recollection

Phosphine gas detected in the clouds of Venus could be a sign of life or some strange unknown chemistry, Lisa Grossman reported in “Possible sign of life is found on Venus” (SN: 10/10/20 & 10/24/20, p. 6).

The story brought back memories for reader Bruce Hapke, a professor of planetary science at the University of Pittsburgh.

“In 1975, my colleague Robert M. Nelson and I published the first high-quality, broadband spectrum of the clouds of Venus … which we obtained using the 106-inch telescope at McDonald Observatory in Texas,” Hapke wrote. “This spectrum turned out to be identical to that of a form of elemental sulfur, and we suggested that tiny particles of sulfur in the clouds are responsible for their yellowish color. The sulfur comes from volcanic eruptions.”

By then, “Russia had launched several unmanned spacecraft that had successfully landed on the surface of

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Dimming Sun’s rays could ease climate impacts in Africa

The 2017 'Day Zero' drought in South Africa left reservoirs barren
The 2017 ‘Day Zero’ drought in South Africa left reservoirs barren

Dialling down the Sun’s heat a notch by injecting billions of shiny sulphur dioxide particles into the stratosphere could curtail devastating drought across parts of Africa, new peer-reviewed research has reported.


This form of solar radiation management would slash the risk of another “Day Zero” drought in Cape Town, South Africa—a city of 3.7 million which ran out of water in 2017—by as much as 90 percent, according to a study published last week in Environmental Research Letters.

Global warming to date—just over one degree Celsius since the mid-19th century—enhances the likelihood of such droughts by a factor of three, earlier research has shown.

Allowing temperatures to increase another degree to 2C above preindustrial levels would triple the risk again.

The 2015 Paris climate treaty, signed by virtually all the world’s nations, calls for capping global warming at

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‘Strange rays’ crowdsourced on social media shed light on black hole illumination

"Strange rays" crowdsourced on social media shed light on black hole illumination
Judy Schmidt, an image processing expert and citizen scientist, processed this image of IC5063—a Seyfert galaxy with an active galactic nuclei—from Barth’s Prop15444 and discovered what looked like dark shadows or cones pointing inward towards the center of the galaxy. Credit: NASA/ESA/A. Barth/J. Schmidt

Sparked by an image uploaded to Twitter, new research indicates that the light produced by black hole accretion may be bright enough to reflect off of dust, illuminating the host galaxy, and creating light and dark rays similar to the effect of crepuscular rays on Earth. The research is published in The Astrophysical Journal Letters.


When a supermassive black hole accretes, or “feeds,” on the matter surrounding it, the resulting release of energy gives off an intense light. Until now, scientists believed that this light only illuminates the parts of a galaxy that fall within narrow ionization cones. But photographic evidence of IC 5063—a radio-loud Seyfert

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