NOCTILUCENT CLOUDS OVER LONDON: On the summer solstice, a midnight display of noctilucent clouds (NLCs) startled sky watchers in London, who could see tendrils of frosted meteor smoke glowing through the city's urban lights. The outbreak over London is a sign that even more intense NLCs are on the way. Indeed, they have already spread to multiple states in the USA including Washington, Oregon, and Idaho. Browse: photo gallery.
MASSIVE SAHARA DUST CLOUD WIPES OUT THE NIGHT SKY: A cloud of dust just swallowed Puerto Rico. "For the past two days, dust from the Sahara desert has filled the air here in the Caribbean," reports Frankie Lucena of Cabo Rojo, Puerto Rico. "I've seen plenty of Saharan dust events, and this is by far the worst one yet. It has completely blocked out most of the stars in our night sky." He took this picture near local midnight on June 21-22:
"Only Jupiter and Saturn (and the Lajas Aerostat) were relatively easy to see," he says. "I wonder if dust storms on Mars would have a similar color if photographed at night."
The dust enveloping Puerto Rico is coming from the Sahara desert thousands of miles away. In a sense, this is nothing unusual. Every year, hundreds of millions of tons of African dust cross the Atlantic. Migrating dust helps build beaches in the Caribbean and fertilizes soils in the Amazon. It can also desiccate thunderclouds and suppress storms. Satellites track African dust meandering over the Caribbean every June and July.
But this particular dust plume is epic--perhaps the most massive in half a century. "Today (June 23rd) we registered the highest level of Saharan Dust in 20 years of data," says Lucena. "Meteorologists also indicated that air quality was at its highest warning level. Many folks in my area decided to stay indoors."
Above: Satellite images show Saharan dust overrunning Puerto Rico, June 18-22. [more]
Later this week, on Thursday or Friday, the dust plume is expected to reach Texas. It won't be as dense as it was in Puerto Rico, but Texans will notice its arrival, bringing milky daytime skies along with vivid sunrises and sunsets. On Saturday, the plume could turn east and drift over southern and mid-Atlantic US states. Got photos? Submit them here.
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COMET NEOWISE IS LOOKING GOOD: Comet NEOWISE (C/2020 F3) is plunging toward the sun for a close encounter near the orbit of Mercury on July 3rd. SOHO coronagraphs are monitoring the approach, and it's looking good:
The sun-baked comet is still intact. Moreover, comparing the comet to nearby reference stars, we see that it is brightening to approximately magnitude +3. This should make Comet NEOWISE a naked-eye object when it emerges from the sun's glare in mid-July. SOHO will be monitoring the comet for the rest of the week, so stay tuned for updates.
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APOLLO 11 PROOF SILVER DOLLAR (COLLECTOR'S ITEM): Are you looking for a far-out gift? Consider this: On July 20, 2019 (the 50th anniversary of the Apollo 11 Moon landing), the students of Earth to Sky Calculus flew this rare proof silver dollar to the stratosphere:
The US Mint created the coins to celebrate the first Moon landing--but you can no longer buy them from the Mint. You can, however, get one from Earth to Sky Calculus. The students are selling the collector's item for $229.95 to support their cosmic ray ballooning program.
The silver dollar is curved and reproduces the helmet of astronaut Buzz Aldrin. Reflected in Buzz's visor are Neil Armstrong, the United States flag, and the lunar lander. The opposite side of the coin shows Neil's iconic footprint on the Moon. Included is a greeting card showing the coin in flight and a certificate of authenticity.
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