Sunset On Pluto

The First Photograph of the Dark Side of the Moon from 1959

With the launch of Sputnik in 1957, the Soviet Union kicked off the Space Race and for the first several years (arguable up until the Moon landing in ‘69), they dominated the United States. One of their “firsts” in the early years was taking the first photo of the dark side of the Moon 60 years ago this month.

Astronomer Kevin Hainline wrote a fascinating account of how the Soviet’s Luna 3 spacecraft took the photo and then transmitted it back to Earth.

First off, Luna 3, the first three-axis stabilized spacecraft, had to reach the Moon to take the pictures, and it had to use a little photocell to orient towards the Moon so that now, while stabilized, it could take the pictures. Which it did. On PHOTOGRAPHIC FILM.

And it gets WILDER because these photos were then moved to a little CHEMICAL PLANT to DEVELOP AND DRY THEM. That’s right, Luna 3 had a little 1 Hour Photo inside. Now you’re thinking, well, how do you get those actual photos back to the Earth?

How indeed? The spacecraft faxed the photos to Earth. A few years later, when the Soviets’ Luna 9 took the first photo on the Moon’s surface and went to transmit it back to Earth, a group in the UK was able to read the signal with a fax machine and the resulting image was published the next day on the front page of the Daily Express.

Three moons of Jupiter : Ganymede, Callisto and Io. Credits : NASA/JPL.

NASA concept art from the Apollo era.

One way the universe might end

My favorite astrophysicist Katie Mack recently reposted a Cosmos article she wrote about a relatively obscure model for the total annihilation of the universe, called “vacuum decay.”

Essentially, what vacuum decay relies on is the fact that we don’t know for sure whether space is in the lowest energy, most stable possible state (a true vacuum) or at an adjacent, slightly higher energy level (a false vacuum). Space could be only metastable, and a random quantum fluctuation or sufficiently high level energy event could push part of the universe from the false vacuum to the true one. This could cause “a bubble of true vacuum that will then expand in all directions at the speed of light. Such a bubble would be lethal.”

It’s compellingly badass, and as Mack notes, frightfully efficient. First, it’s not the slow petering out that is heat death. Also, it wouldn’t just eliminate our current universe, but all possibility of a universe anything like ours. Vacuum decay destroys space like Roman generals salting the earth at Carthage.

The walls of the true vacuum bubble would expand in all directions at the speed of light. You wouldn’t see it coming. The walls can contain a huge amount of energy, so you might be incinerated as the bubble wall ploughed through you. Different vacuum states have different constants of nature, so the basic structure of matter might also be disastrously altered. But it could be even worse: in 1980, theoretical physicists Sidney Coleman and Frank De Luccia calculated for the first time that any bubble of true vacuum would immediately suffer total gravitational collapse.

They say: “This is disheartening. The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in a new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it.

"However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some creatures capable of knowing joy. This possibility has now been eliminated.”

Space Probes

The Spaceprob.es site tracks the active probes in operation in and around our solar system, from Voyager I (19.56 billion km from Earth) to the Artemis probes (358,000 km away). (via @BadAstronomer)

Mountains on the Moon (actually Pluto)

Jennifer Daniel

Space Shuttle Endeavour mounted atop one of NASA’s modified Boeing 747 Shuttle Carrier Aircraft.

Celestial Geometry: Equinoxes and Eclipses

March 20 marks the spring equinox. It’s the first day of astronomical spring in the Northern Hemisphere, and one of two days a year when day and night are just about equal lengths across the globe.

Because Earth is tilted on its axis, there are only two days a year when the sun shines down exactly over the equator, and the day/night line – called the terminator – runs straight from north to south.

In the Northern Hemisphere, the March equinox marks the beginning of spring – meaning that our half of Earth is slowly tilting towards the sun, giving us longer days and more sunlight, and moving us out of winter and into spring and summer.

An equinox is the product of celestial geometry, and there’s another big celestial event coming up later this year: a total solar eclipse.

A solar eclipse happens when the moon blocks our view of the sun. This can only happen at a new moon, the period about once each month when the moon’s orbit positions it between the sun and Earth — but solar eclipses don’t happen every month.  

The moon’s orbit around Earth is inclined, so, from Earth’s view, on most months we see the moon passing above or below the sun. A solar eclipse happens only on those new moons where the alignment of all three bodies are in a perfectly straight line.

On Aug. 21, 2017, a total solar eclipse will be visible in the US along a narrow, 70-mile-wide path that runs from Oregon to South Carolina. Throughout the rest of North America – and even in parts of South America, Africa, Europe and Asia – the moon will partially obscure the sun.

Within the path of totality, the moon will completely cover the sun’s overwhelmingly bright face, revealing the relatively faint outer atmosphere, called the corona, for seconds or minutes, depending on location.

It’s essential to observe eye safety during an eclipse. Though it’s safe to look at the eclipse ONLY during the brief seconds of totality, you must use a proper solar filter or indirect viewing method when any part of the sun’s surface is exposed – whether during the partial phases of an eclipse, or just on a regular day.

Learn more about the August eclipse at eclipse2017.nasa.gov.

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