Measuring the speed of light and the moon distance with an occultation of Mars by the Moon

a Citizen Astronomy Campaign

Zuluaga et al
In July 5th 2014 an occultation of Mars by the Moon was visible in South America.
Citizen scientists and professional astronomers in Colombia, Venezuela and Chile performed a set of simple observations of the phenomenon aimed to measure the speed of light and lunar distance.
This initiative is part of the so called “Aristarchus Campaign”, a citizen astronomy project aimed to reproduce observations and measurements made by astronomers of the past.
Participants in the campaign used simple astronomical instruments (binoculars or small telescopes) and other electronic gadgets (cell-phones and digital cameras) to measure occultation times and to take high resolution videos and pictures.
In this paper we describe the results of the Aristarchus Campaign.
We compiled 9 sets of observations from sites separated by distances as large as 2,500 km. We achieve at measuring the speed of light in vacuum and lunar distance with uncertainties of few percent.
The goal of the Aristarchus Campaigns is not to provide improved values of well-known astronomical and physical quantities, but to demonstrate how the public could be engaged in scientific endeavors using simple instrumentation and readily available technological devices.
These initiatives could benefit amateur communities in developing countries increasing their awareness towards their actual capabilities for collaboratively obtaining useful astronomical data.
This kind of exercises would prepare them for facing future and more advanced observational campaigns where their role could be crucial.
Read nore at http://arxiv.org/abs/1506.00346

The simplest method to measure the geocentric lunar distance

a case of citizen science

When the moon rises its distance to an observer in the surface of the Earth is reduced. Objects are not shown to scale.

When the moon rises its distance to an observer in the surface of the Earth is reduced. Objects are not shown to scale.

Jorge I. Zuluaga , Juan C. Figueroa, Ignacio Ferrin

We present the results of measuring the geocentric lunar distance using what we propose is the simplest method to achieve a precise result.
Although lunar distance has been systematically measured to a precision of few millimeters using powerful lasers and retroreflectors installed on the moon by the Apollo missions, the method devised and applied here can be readily used by nonscientist citizens (e.g. amateur astronomers or students) and it requires only a good digital camera.
After launching a citizen science project called the Aristarchus Campaign, intended to involve astronomy enthusiasts in scientific measurement of the Lunar Eclipse of 15 April 2014, we compiled and measured a series of pictures obtained by one of us (J.C. Figueroa).
These measurements allowed us to estimate the lunar distance to a precision of 3%. We describe here how to perform the measurements and the method to calculate from them the geocentric lunar distance using only the pictures time stamps and a precise measurement of the instantaneous lunar apparent diameter. Our aim here is not to provide any improved measurement of a well-known astronomical quantity, but rather to demonstrate how the public could be engaged in scientific endeavors and how using simple instrumentation and readily available technological devices such as smartphones and digital cameras, any person can measure the local Universe as ancient astronomers did…
… Read more at http://arxiv.org/ftp/arxiv/papers/1405/1405.4580.pdf

NASA's lunar monitoring program has detected hundreds of meteoroid impacts. The brightest, detected on March 17, 2013, in Mare Imbrium, is marked by the red square.

Bright explosion on the Moon

NASA's lunar monitoring program has detected hundreds of meteoroid impacts. The brightest, detected on March 17, 2013, in Mare Imbrium, is marked by the red square.

NASA’s lunar monitoring program has detected hundreds of meteoroid impacts. The brightest, detected on March 17, 2013, in Mare Imbrium, is marked by the red square.

For the past 8 years, NASA astronomers have been monitoring the Moon for signs of explosions caused by meteoroids hitting the lunar surface. “Lunar meteor showers” have turned out to be more common than anyone expected, with hundreds of detectable impacts occurring every year.
They’ve just seen the biggest explosion in the history of the program.
“On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium,” says Bill Cooke of NASA’s Meteoroid Environment Office. “It exploded in a flash nearly 10 times as bright as anything we’ve ever seen before.”
Anyone looking at the Moon at the moment of impact could have seen the explosion—no telescope required. For about one second, the impact site was glowing like a 4th magnitude star.
Ron Suggs, an analyst at the Marshall Space Flight Center, was the first to notice the impact in a digital video recorded by one of the monitoring program’s 14-inch telescopes. “It jumped right out at me, it was so bright,” he recalls.
The 40 kg meteoroid measuring 0.3 to 0.4 meters wide hit the Moon traveling 56,000 mph. The resulting explosion1 packed as much punch as 5 tons of TNT.

Cooke believes the lunar impact might have been part of a much larger event.
“On the night of March 17, NASA and University of Western Ontario all-sky cameras picked up an unusual number of deep-penetrating meteors right here on Earth,” he says. “These fireballs were traveling along nearly identical orbits between Earth and the asteroid belt.”

This means Earth and the Moon were pelted by meteoroids at about the same time.
“My working hypothesis is that the two events are related, and that this constitutes a short duration cluster of material encountered by the Earth-Moon system,” says Cooke

One of the goals of the lunar monitoring program is to identify new streams of space debris that pose a potential threat to the Earth-Moon system. The March 17th event seems to be a good candidate.
Controllers of NASA’s Lunar Reconnaissance Orbiter have been notified of the strike. The crater could be as wide as 20 meters, which would make it an easy target for LRO the next time the spacecraft passes over the impact site. Comparing the size of the crater to the brightness of the flash would give researchers a valuable “ground truth” measurement to validate lunar impact models.

Unlike Earth, which has an atmosphere to protect it, the Moon is airless and exposed. “Lunar meteors” crash into the ground with fair frequency. Since the monitoring program began in 2005, NASA’s lunar impact team has detected more than 300 strikes, most orders of magnitude fainter than the March 17th event. Statistically speaking, more than half of all lunar meteors come from known meteoroid streams such as the Perseids and Leonids. The rest are sporadic meteors—random bits of comet and asteroid debris of unknown parentage.
U.S. Space Exploration Policy eventually calls for extended astronaut stays on the lunar surface. Identifying the sources of lunar meteors and measuring their impact rates gives future lunar explorers an idea of what to expect. Is it safe to go on a moonwalk, or not? The middle of March might be a good time to stay inside.
“We’ll be keeping an eye out for signs of a repeat performance next year when the Earth-Moon system passes through the same region of space,” says Cooke. “Meanwhile, our analysis of the March 17th event continues.”

Read more at: http://phys.org/news/2013-05-bright-explosion-moon.html#jCp

crater

The Moon’s Permanently Shadowed Regions

craterAs you watch the Moon over the course of a month, you’ll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun’s light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA’s Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail.

This video is public domain and can be downloaded at:http://svs.gsfc.nasa.gov/goto?11218

Distance cues to the horizon allow our perception to estimate the distance to the sky, 
resulting in a strong illusory phenomenon. Absence of distance cues at the zenith cause our 
perception to be unable to estimate distance to the sky, resulting in a weak illusory phenomenon.

Binocular disparity as an explanation for the moon illusion

Distance cues to the horizon allow our perception to estimate the distance to the sky, resulting in a strong illusory phenomenon. Absence of distance cues at the zenith cause our  perception to be unable to estimate distance to the sky, resulting in a weak illusory phenomenon.

Distance cues to the horizon allow our perception to estimate the distance to the sky,
resulting in a strong illusory phenomenon. Absence of distance cues at the zenith cause our
perception to be unable to estimate distance to the sky, resulting in a weak illusory phenomenon.

Joseph Antonides, Toshiro Kubota
We present another explanation for the moon illusion, in which the moon looks larger near the horizon than near the zenith. In our model, the sky is considered a spatially contiguous and geometrically smooth surface. When an object (like the moon) breaks the contiguity of the surface, humans perceive an occlusion of the surface rather than an object appearing through a hole. Binocular vision dictates that the moon is distant, but this perception model dictates that the moon is closer than the sky. To solve the dilemma, the brain distorts the projections of the moon to increase the binocular disparity, which results in increase of the angular size of the moon. The degree of the distortion depends upon the apparent distance to the sky, which is influenced by the surrounding objects and the condition of the sky. The closer the sky appears, the stronger the illusion. At the zenith, few distance cues are present, causing difficulty with distance estimation and weakening the illusion.
Read more: http://arxiv.org/ftp/arxiv/papers/1301/1301.2715.pdf

moon

The moon’s phase and libration throughout the year 2013

This visualization shows the moon’s phase and libration throughout the year 2013, at hourly intervals. Each frame represents one hour. In addition, this visualization also shows other relevant information, including moon orbit position, subearth and subsolar points, distance from the Earth. Click each graphic to learn more about what it means! Finally, to learn more about this visualization, or to see what the moon will look like at any hour in 2013, visit http://svs.gsfc.nasa.gov/goto?4000!


http://youtu.be/ixroBOCm8M8