Solar Eclipse Explorer App

Eclipse on Cue

2017-07-27T13:53:00.000-07:00

New Eclipse Explorer Audio Cues:
What you’ll see (and hear) during the eclipse!

No matter where you are in North America on August 21, 2017 the new audio cues feature will guide you through the Great American Total Eclipse of 2017. Read on to learn what you will see and now hear during the solar eclipse.

Warning: Using event timers and audio cues never implies it is safe to take off any type of eye protection at any time when observing the Sun. This app’s calculations are estimations and are not guaranteed. Please use caution, as it is never safe to view the Sun (eclipsed or otherwise) without proper and certified eye protection.

To demonstrate all audio cues, you may “time travel” by long-pressing an eclipse circumstance such as “Partial Eclipse Begins” or “Total Eclipse Begins”.

Long press circumstances for time travel mode and audio cue demo.

Audio cues may be turned on or off in the app drawer menu on the left. Turning on the audio cues will play the “Three Beep Cue” for demo purposes and app volume awareness.

Voice Cues: You will hear a voice say each eclipse circumstance approximately 7 to 10 seconds before the occurrence begins.

The Three Beep Cue: As eclipse circumstances occur you will hear two longer tones and a final third higher pitched short beep. The third beep marks, as accurately as is possible, the actual start of each eclipse occurrence.

Eclipse Events and Cues

“First Contact” (Cue Beeps) (Occurs in all locations in North America): This is the moment the eclipse starts as the Moon first “contacts” the solar disk as observed from your location. In reality, you probably will not see anything, as it usually takes a few minutes for the first “bite” out of the Sun to be visible.

Crescent shaped solar images created by the shadow of a tree.

For those outside the path of totality, the partial solar eclipse is still worth viewing. In almost all locations in the United States, the Sun will be covered enough so that it will be noticeably darker. No dramatic darkening, per se, but just enough to notice. In fact, it will also be enough to cool the air temperature, providing some relief for a hot, August afternoon. A safe and properly filtered view of the eclipse will reveal the jagged edges of the Moon back-lit by the Sun. Shadows cast by trees will reveal thousands of crescent shaped solar eclipse images. As the solar image itself is no longer round, but crescent-shaped, your own shadow will look rough and odd. While partial solar eclipses are fairly regular occurrences, such a deep magnitude partial solar eclipse is still fairly rare and worth at least of few moments to enjoy.

“Look for Shadow Bands” (Only visible from the narrow path of totality): Possibly observed 45 seconds prior to second contact, then again after third contact for up to 45 seconds.

Artistic rendition of shadow bands.

As the Moon covers most of the Sun and only a small narrow sliver of light is left, the phenomenon of shadow bands may occur. They are best viewed on a smooth, light-colored surface on the ground and can often look like the shimmering bands of light seen on the bottom of a swimming pool. They may not always be visible, but in some cases can be strong enough for children to chase after them. Most scientist believe shadow bands are caused by normal atmospheric turbulence. However, a recent hypothesis has suggested that the eclipse itself causes the shadow bands: As the Moon’s shadow races across the Earth at thousands of miles per hour, it is known to cause atmospheric cooling. Therefore, a relatively cool area of atmosphere is being created at hyper-sonic velocities creating a bow shock . The last narrow sliver of sunlight passes through these bow-shock waves creating the shadow bands effect. More information is required to prove this hypothesis. It may be possible that this eclipse, itself, will provide enough evidence.

“Look for Baily’s Beads” (Only visible from the narrow path of totality): Observed approximately 20 seconds prior to second contact, then again after third contact for another 20 seconds. As the Moon is now almost completely covering the solar disk, just a few specs of light continue to shine through the rough surface of the Moon. From a naked-eye perspective, the Moon looks almost perfectly smooth: However, in reality, the Moon’s surface is complicated by craters, canyons, valleys, and mountains. As the Sun shines through these irregularities on the lunar surface, they are presented as beads of light.

“Look for diamond ring effect” (Only visible from the narrow path of totality): Mere seconds before second contact to seconds after third contact.

Also known as The last Baily’s Bead: Right before the Sun is completely covered by the Moon, one last bit of sunlight finds its way through a valley or canyon on the Moon. The Sun’s corona just starts to become visible. Now the entire circular outline of the Moon is visible with one bright spot of light: Hence, a ring-like structure with one bright diamond-like bit of sunlight is visible.

“Second Contact (Cue Beeps)” (Only occurs from the narrow path of totality): The Moon has now completely covered the Sun and totality has begun. The air has cooled and the near darkness of a night sky in the middle of the day occurs. Bright stars and planets will be visible. The Sun’s atmosphere, the corona, is visible and surrounds the Moon as a bright wispy cloud-like structure. Close-in views of the totally-eclipsed Sun will reveal solar flares peaking out around the Moon.

“Mid Eclipse (Cue Beeps)” (Occurs in all locations in North America): This is the half-way point of the eclipse. If you are not in the path of totality then this is the point at which the Sun is most eclipsed. In the path of totality this is when the Sun and Moon are most aligned.

“Third Contact (Cue Beeps)” (Only occurs from the narrow path of totality): Totality has now ended and Moon has begun to reveal the Sun again. The diamond ring effect, Baily’s Beads, and shadow bands may be visible in the reverse order they were seen prior to second contact. Due to the quick reverse-succession of these phenomenon, no voice cues will be heard.

“Fourth Contact (Cue Beeps)” (Occurs in all locations in North America): The eclipse has ended. The Moon no longer covers any part of the Sun. Time to start planning your next eclipse adventure.

The New Eclipse Explorer App

2017-06-27T10:47:00.000-07:00

After a long and nearly complete code rewrite, the Eclipse Explorer Mobile App: Version 3.0 is now available: Just in time for the Great American Solar Eclipse of 2017! Read on for further information.

App screen shot.

What is Eclipse Explorer?
Eclipse Explorer is a free astronomical app that allows you to view the circumstances for solar eclipses that occur between 1900 and 2100 using your GPS defined location. It uniquely features countdown timers to eclipse events at your specific location, simulates the position of the Sun and Moon, and draws the location of the Moon's shadow on the Earth in real-time. Lookup solar eclipse circumstance data from around the world: Touch your desired location or lookup by city/point of interest/address.

Why Create Eclipse Explorer?
There are numerous online sources for eclipse circumstances, however, very few are mobile friendly and easily integrate with a mobile device which often offers very accurate time and location to the user: An integrated GPS.

See the Spectacle
A solar eclipse is one of nature's most amazing spectacles, however, clouds can ruin your day. Use this app to overlay satellite and radar data on the day of the eclipse to make sure you stay within the path of totality and away from the clouds!

A Code Demonstration
In terms of coding and application development, it is a demonstration of what can be achieved inside a completely cross-platform standard JavaScript framework.

Coding Eccentricities

2017-06-26T14:06:00.000-07:00

Standing in the Shadow of the Moon

Solar eclipses offer the unique ability to stand in the shadow of a massive solar system body. When that moment of totality (or annularity) occurs you get the opportunity to witness the simultaneous sunsets and sunrises on another planetary body. The unique geometry of our Earth-Moon system allows us to view this rare spectacle as the perceived lunar size is nearly the exactly the same as of the Sun: There’s no other place in the solar system where this occurs.

Solar Eclipse Diagram

the orbit of the Moon is planar and the geometry of it’s shadow is conical, when cast on another rotating spherical body, the Earth, the lunar shadow is contorted into unique and odd shapes. During a solar eclipse, the shadow of the Moon is rarely circular, and is often an odd ellipsoid shape that races from 10,000 to 2000 mph across the surface of the Earth. NASA has provided excellent animations of the Moon’s traversal across the globe during eclipses. I find it interesting that such a perfectly round object moving in a nearly perfect plane can create such oddly fascinating tracks across our planet.

NASA’s online animated shadow: Can non-astronomer/non-professional developer recreate this?

During a total eclipse, especially from an elevated location, it is possible to witness the lunar shadow race toward you: I want to know it is coming!

I made it my endeavor to see if it was possible to recreate this NASA’s shadow images using the somewhat limited computing power of a mobile phone. I wanted something that was self-contained and worked in an environment without an online connection. Other websites and apps often use pre-computed points to display an eclipse circumstance map. My app differs from this approach as it only stores a small set of Besselian elements (28 floating point numbers per eclipse) that compute the entire eclipse map and animated shadow.

The Moon’s shadow near sunset from an annular solar eclipse in January 1992 as calculated by Eclipse Explorer.

While there were plenty of online resources to use Besselian elements to compute eclipse times and circumstances for a particular spot on Earth, I was at a loss to find resources to construct eclipse maps and shadow dynamics. Being neither an astronomer, mathematical expert, or even a full time software developer I gave it my best.

In the end, I used JavaScript’s somewhat new ability to spawn multiple parallelcomputations to scan and interpolate points that create the maps and animations you see in the Eclipse Explorer App. It’s not a perfect solution, and there are other and possibly better ways to make these computations, but it was a fantastic learning experience. I expanded my software development skills while digging around in trigonometric math that I haven’t dealt with in years (or ever).