Podcasts

I listen to a lot of podcasts and thought I might start mentioning my favorites here.

I’ll begin with two recently listened to. The TED Radio Hour is a favorite and one of the latest episodes is a perfect example of why I enjoy it so much. Hardwired. I’ve given it a listen but will need to give it a second. I always know a podcast is great when many of the episodes require at least a second listen.

Another favorite, Science Friday, has, as usual, aired another excellent episode. In particular I enjoyed the segments on Voyager which included a wonderful interview with planetary scientist Carolyn Porco as well as the segment on indoor microbiomes. Fascinating stuff. Check it out.

Back to the night sky

I started observing the night sky in late 2012 and kept up a pretty steady pace until about 12 months ago when my observing time shrank drastically. Partly due to weather, also due to a lack of effort on my part. I’m hoping to turn that around. I doubt I’ll be logging the 6 hour observing sessions I was doing in the first couple of years but I’d at least like to get in a couple hours when the skies are clear. Like many things in life, I find that when I make the effort my passion and interest deepen. When I fail to make the effort, they fade. My interest in observational astronomy is interwoven with my interest in cosmology, chemistry, physics and other related areas. These are not interests I am willing to give up due to laziness.

So, I logged a few sessions this past week. Right now our night sky faces in towards the Milky Way so lots of globular clusters and nebulae are visible. Oh, also, Saturn. Had a good, long look at Saturn. Then I spent a couple hours each night looking at globular clusters in Sagittarius, Pegasus (M15), and M2 in Aquarius.

 If you’ve never looked at a globular cluster and you get time with a telescope make sure you find one. They are fantastic to see in a medium to large amateur telescope, one of the best objects to view. They are equally amazing to learn about. For example M2, one of the oldest known clusters at 13 billion years, is also one of the larger globular clusters and is 175 light years in diameter. Within that space there are 150,000 stars. In other words, it is very densely packed with very old stars. Viewing it with my 12″ dobsonian scope with an 11mm eyepiece resolves many of the stars and the result is stunning.

These stars are nearly as old as the Universe and, as I understand it, still remain a bit of a mystery in terms of how they came to be in clusters orbiting galaxies. Our galaxy has about 150 such clusters. They typically reside outside the disk of the galaxy and orbit the galactic core as satellites with an orbit radius of 130,000 light years. The Andromeda Galaxy is thought to have as many as 500 such globular clusters.

Speaking of our neighbor, I also had a nice long look at Andromeda. As always, a beautiful galaxy to look at through even a small scope.

Eclipse

Like many, I spent my Monday afternoon observing the moon cross between the Earth and the sun. My cabin is located in the path of the totality. I had 1:40 of totality and was lucky enough to share it with a handful of friends under clear skies.

To put it simply, it was absolutely glorious.

Voyager at 40

A great thread by @justinhendrix over on Twitter:

The solar eclipse Monday is set to overshadow another significant event for space nerds like me. Tomorrow, August 20th, is a special day.

August 20th is the 40th anniversary of the 1977 launch of @NSFVoyager2, the first of two Voyager probes to explore the outer planets.

Its sister probe, Voyager 1, was launched 16 days later. These two probes represent one of humanity’s most extraordinary achievements.

Voyager 1 is nearly 13 billion miles from Earth; it takes a ray of light more than 19 hours to travel from here to its position.

Voyager 2 is nearly 11 billion miles and 16 light hours away. 5 years ago Voyager 1 entered interstellar space, on 25 August 2012.

Incredibly, both spacecraft are still sending scientific information about their surroundings through the Deep Space Network.

In the late 1960s that NASA determined a once-every–176 year alignment would allow a spacecraft to to visit all four outer planets.

Voyager delivered the first single frame photo of the Earth and the Moon together from space. https://twitter.com/justinhendrix/status/898891148495912962/photo/1

The probes carried radioisotope thermoelectric generators powered by plutonium, and carry an array of scientific instruments. https://twitter.com/justinhendrix/status/898891697496637441/photo/1

The computers aboard the Voyager probes each have 69.63 kilobytes of memory in total. That’s about enough to store one average .jpg.

The probes used assembly languages such as FORTRAN. Recently the Voyager program hired a new FORTRAN programmer. http://www.popularmechanics.com/space/a17991/voyager–1-voyager–2-retiring-engineer/

The probes visited all the giant outer planets, including Jupiter, Saturn, Uranus and Neptune. They made numerous important discoveries.

For instance, erupting volcanoes on Jupiter’s moon Io, the first evidence of volcanic activity elsewhere in the solar system. Alt text

The volcanos on Io were discovered by a JPL Voyager imaging scientist named Linda Moribito Kelly. http://www.planetary.org/blogs/guest-blogs/a-j-s-rayl/stories_kelly.html

Voyager discovered an ocean beneath the icy crust of Jupiter’s moon Europa, waves and fine structure in Saturn’s icy rings, Neptune’s…

Great Dark Spot and 1,600 kilometer-per-hour winds, geysers erupting from the polar cap Neptune’s moon Triton, and eventually…

The termination shock where supersonic solar wind slows down, forming the final frontier of the solar system. http://ibex.swri.edu/students/What_is_the_termination.shtml

You can see many of the images that the Voyagers took during their trek through the outer planets here: https://www.jpl.nasa.gov/voyager/galleries/images-voyager-took/

Jupiter. https://twitter.com/justinhendrix/status/898897243201167360/photo/1

Saturn. https://twitter.com/justinhendrix/status/898897459061174273/photo/1

Uranus. https://twitter.com/justinhendrix/status/898897744714190848/photo/1

Neptune. https://twitter.com/justinhendrix/status/898902872473186304/photo/1

And the famous Pale Blue Dot photo, which inspired Carl Sagan’s speech, which we should all listen to & consider https://www.youtube.com/watch?time_continue=1&v=p86BPM1GV8M

The Voyagers also famously carry a Golden Record, which carries the sounds of earth into space- Sagan’s idea. http://www.npr.org/2017/08/11/542867050/40-years-ago-nasa-launched-message-to-aliens-into-deep-space

Blind Willie Johnson’s ‘Dark Was the Night, Cold Was the Ground’ is one of the songs now in interstellar space https://www.youtube.com/watch?v=V8AuYmID4wc

The Voyagers represent the best of humanity. The best scientific thinking, engineering, ambition, curiosity, passion, arts and culture.

We’d do well at this moment, 40 years hence, to look at the legacy of these probes, and consider what we can learn from their journey.

It’s more than the sum of their scientific discoveries. They explore the universe, but they also tell us something about ourselves.

Our best selves. Voyager is the best of humanity. We need to remember the aspiration to be our best selves, to advance the species.

So enjoy the eclipse, but spare a moment tomorrow at 10:29 AM Eastern to remember the launch of @NSFVoyager2, a great human achievement.

Here is an excellent hour on the history of Voyager from the BBC. h/t @acinonnap http://www.bbc.co.uk/programmes/w3csvntg

Understanding the eclipse by creating a to-scale demonstration of orbits and moon phases

I was recently asked to do a presentation about the upcoming solar eclipse at our library as I am one of a small local group of amateur astronomers. I happily accepted. I always enjoy putting together Keynote presentations for such events. I spent several days last week assembling the 38 slide presentation and did the presentation last night. It seemed to go well. For one part of the presentation I used three volunteers to serve as the sun, moon, and Earth. The idea was to illustrate the phases of the moon as well as the angle of the moon’s orbit with these three people and in truth, after a bit of initial confusion, I think it went pretty well. But it wasn’t to scale as we were crowded into a fairly small room at the library. After the event I got to thinking about how that sort of presentation, in particular the bit involving the volunteers, could be expanded into something really fun but in an outside location so that a sense of scale could be created. It would involve a bit of math so I thought it might be fun to recruit Siri as my helper in preparing this activity.

The idea would be to create a scale model of the Earth in relation to the sun and moon based on a circle of 365 feet in circumference. Each foot represented one day in the Earth’s orbit around the sun. Now, at this scale, I wanted to properly represent the position the sun at the center of our orbit. I needed the radius of my circle. Okay. I asked Siri to calculate the radius of a circle with a circumference of 365 feet. I was given a WolframAlpha calculation screen as a result: 58.1 feet. But I wondered if I could copy/paste the content. It had never occurred to me to tap the WolframAlpha icon, just a bit of text in a square in the corner of that display of results. I’ve done this kind of thing many times but never thought to see what would happen if I tapped. I expected it would do nothing. Instead, it took me to the AppStore for the WolframAlpha app. It never occurred to me that there was such an app but of course there is! I downloaded it and it opened my results into the app. It’s a very nice app that allows further input and new calculations among many other things. But no option to copy/paste the content.

Now, back to working out the activity. I’ll need to get some string but before that, I now know that if my orbit is scaled to 365, feet my radius is 58.1 feet. So, I’ll position my sun with a pole with string tied to it. From there I’ll walk out 58.1 feet and place another pole. I’ll have two strings. One which I’ll keep tied to the center pole (my sun) and which will guide my “orbit”. The second string will be tied to the second pole. Now it’s just a matter of walking the circle around the sun and dropping my string to represent the 365 feet of orbit. The next step is to convert a few other distances. For this I hopped over to this solar system scale model calculator.

Next, I used Siri to do a bit of math. First I asked her for the average circumference of the Earth’s orbit. Then I asked her to convert this from miles into feet. Then I divided that by 365 come up with my model scale of 8,447,618,973. With that number input into the solar system scale calculator I confirmed my Earth orbit radius of 58.1 in the results. Next, I wanted to get the moon’s orbit as well as the size of my three solar system objects at this scale. I made sure to select the Moons option and on the form and I got an orbit radius for the moon of 1.79 inches. TINY!! With that radius the average circumference of the lunar orbit is just 11.25 inches. Whats’ the size of the sun, Earth and moon at this scale? According to this same calculator, at this scale the sun is just 6.49 inches in diameter. Of course, the Earth and moon are very tiny! The Earth is just .06 inches in diameter and the moon is .016. Just a spec.

So, I’ve got the scale though in truth it might be best done at a slightly larger scale given how tiny the Earth and moon are in this model. Regardless of the ultimate scale of the model it is fun to play with and I expect it will be a fun model to explore in the yard. The idea would be to set the scale and then discuss the movement of the moon in it’s orbit of the Earth and the Earth’s orbit around the sun. By positioning volunteers it becomes a bit more obvious why a new moon is invisible to us. By adjusting the position of the volunteer “moon” in orbit around the volunteer “Earth” it become easier to understand how the moon gradually becomes more visible as a crescent then a quarter then a full moon and so on. Further discussion of the 5° elevation of the moon off of the ecliptic helps participants further understand why we do not have solar eclipses with every new moon.

Denny

August 16, 2017

With the recent events in Charlottesville, Virginia and Trump’s predictable lack of condemnation, which is to say, support for, white supremacy, I can’t help but believe that America is now entering a new depth of crisis.

This could get very bad.

Pale Blue Dot


With all of the craziness of the past couple of days (and really, the months since DT took office) it’s good to get some perspective with Carl Sagan.

The original image was taken in 1990 at Sagan’s request. I used the new image taken July 19, 2013 by the Cassini spacecraft in an event called “The Day the Earth Smiled”. Look closely at DOT and you’ll find the Earth at the center. 

Story behind original image taken in 1990 at Penny4Nasa.