Sunday, July 21, 2019

HDR: Earths Circular Shadow on the Moon

What could create such a large circular shadow on the Moon? The Earth. Last week's full Moon -- the Buck Moon -- was so full that it fell almost exactly in a line with the Sun and the Earth. When that happens the Earth casts its shadow onto the Moon. The circularity of the Earth's shadow on the Moon was commented on by Aristotle and so has been noticed since at least the 4th century BC. What's new is humanity's ability to record this shadow with such high dynamic range (HDR). The featured HDR composite of last week's partial lunar eclipse combines 15 images and include an exposure as short as 1/400th of a second -- so as not to overexpose the brightest part -- and an exposure that lasted five seconds -- to bring up the dimmest part. This dimmest part -- inside Earth's umbra -- is not completely dark because some light is refracted through the Earth's atmosphere onto the Moon. A total lunar eclipse will occur next in 2021 May. via NASA

Saturday, July 20, 2019

Moonquakes Surprisingly Common

Why are there so many moonquakes? Analyses of seismometers left on the moon by the Apollo moon landings reveals a surprising number of moonquakes occurring within 100 kilometers of the surface. In fact, 62 moonquakes were detected in data recorded between 1972 and 1977. Many of these moonquakes are not only strong enough to move furniture in a lunar apartment, but the stiff rock of the moon continues to vibrate for many minutes, significantly longer than the softer rock earthquakes on Earth. The cause of the moonquakes remains unknown, but a leading hypothesis is the collapse of underground faults. Regardless of the source, future moon dwellings need to be built to withstand the frequent shakings. Pictured here 50 years ago today, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed lunar seismometer, looking back toward the lunar landing module. via NASA

Wednesday, July 17, 2019

Shadowed Moon and Mountain

On July 16 the Moon celebrated the 50th anniversary of the launch of Apollo 11 with a lunar eclipse visible from much of planet Earth. In this view part of the lunar disk is immersed in Earth's dark, reddened umbral shadow. Near the maximum eclipse phase, it just touches down along a mountain ridge. The rugged Tyrolean nightscape was recorded after moonrise south of Innsbruck, Austria with a dramatically lit communication tower along the ridgeline. Of course eclipses rarely travel alone. This partial lunar eclipse was at the Full Moon following July 2nd's New Moon and total eclipse of the Sun. via NASA

Tuesday, July 16, 2019

Apollo 11: Descent to the Moon

It had never been done before. But with the words "You're Go for landing", 50 years ago this Saturday, Apollo 11 astronauts Aldrin and Armstrong were cleared to make the first try. The next few minutes would contain more than a bit of drama, as an unexpected boulder field and an unacceptably sloping crater loomed below. With fuel dwindling, Armstrong coolly rocketed the lander above the lunar surface as he looked for a clear and flat place to land. With only seconds of fuel remaining, and with the help of Aldrin and mission control calling out data, Armstrong finally found a safe spot -- and put the Eagle down. Many people on Earth listening to the live audio felt great relief on hearing "The Eagle has landed", and great pride knowing that for the first time ever, human beings were on the Moon. Combined in the featured descent video are two audio feeds, a video feed similar to what the astronauts saw, captions of the dialog, and data including the tilt of the Eagle lander. The video concludes with the panorama of the lunar landscape visible outside the Eagle. A few hours later, hundreds of millions of people across planet Earth, drawn together as a single species, watched fellow humans walk on the Moon. via NASA

Monday, July 15, 2019

Apollo 11 Launches Humans to the Moon

Everybody saw the Moon. Nobody had ever been there. Humans across planet Earth watched in awe 50 years ago today as a powerful Saturn V rocket attempted to launch humans -- to the Moon. Some in space flight guessed that the machinery was so complex, that so many things had to go right for it to work, that Apollo 11 would end up being another useful dress rehearsal for a later successful Moon-landing mission. But to the Moon they went. The featured video starts by showing astronauts Aldrin, Armstrong, and Collins making their way to the waiting rocket. As the large and mighty Saturn V launched, crowds watched from Cape Canaveral in Florida, USA and on television around the world. The events that unfolded over the next few days, including a dramatic moon walk 50 years ago this Saturday, will forever be remembered as a milestone in human history and an unrivaled demonstration of human ingenuity. This week, many places around the world are planning celebrations of the 50th anniversary of the first humans landing on the Moon. via NASA

Saturday, July 13, 2019

Eagle Aurora over Norway

What's that in the sky? An aurora. A large coronal mass ejection occurred on our Sun five days before this 2012 image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth. Although most of this cloud passed above the Earth, some of it impacted our Earth's magnetosphere and resulted in spectacular auroras being seen at high northern latitudes. Featured here is a particularly photogenic auroral corona captured above Grotfjord, Norway. To some, this shimmering green glow of recombining atmospheric oxygen might appear as a large eagle, but feel free to share what it looks like to you. Although the Sun is near Solar Minimum, streams of the solar wind continue to impact the Earth and create impressive auroras visible even last week. via NASA

Friday, July 12, 2019

The Eagle Rises

Get out your red/blue glasses and check out this stereo view from lunar orbit. The 3D anaglyph was created from two photographs (AS11-44-6633, AS11-44-6634) taken by astronaut Michael Collins during the 1969 Apollo 11 mission. It features the lunar module ascent stage, dubbed The Eagle, rising to meet the command module in lunar orbit on July 21. Aboard the ascent stage are Neil Armstrong and Buzz Aldrin, the first to walk on the Moon. The smooth, dark area on the lunar surface is Mare Smythii located just below the equator on the extreme eastern edge of the Moon's near side. Poised beyond the lunar horizon is our fair planet Earth. via NASA