Moon Archives

May 4, 2012December 23, 2015 by Nancy Atkinson

How the Hubble Telescope Will Look at the Moon to See Venus Transit the Sun

Scientists used the Hubble Space Telescope to look at the Moon to prepare for special observations of the 2012 Venus transit of the Sun. Credit: NASA, ESA, and D. Ehrenreich (Institut de Planetologie et d'Astrophysique de Grenoble (IPAG)/CNRS/Universite Joseph Fourier)

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Venus moving across the face of the Sun, from our vantage point here on Earth, is such a rare event, that astronomers and observatories around the world have been preparing for this year’s Venus Transit, on June 5-6. And one observatory that is literally “around the world,” – the Hubble Space Telescope — is even planning to make observations of this transit event. What, you say? The Hubble telescope can’t look at the Sun – it would fry every component on board! Hubble scientists are being pretty sneaky, if not resourceful so they too can join in the observations.

Since Hubble can’t look at the Sun directly, astronomers are planning to point the telescope at the Moon, using it as a mirror to capture reflected sunlight and isolate the small fraction of the light that passes through Venus’s atmosphere. Imprinted on that small amount of light are the fingerprints of the planet’s atmospheric makeup.

Scientists say these observations will mimic a technique that is already being used to sample the atmospheres of giant planets outside our solar system passing in front of their stars. In the case of the Venus transit observations, astronomers already know the chemical makeup of Venus’s atmosphere, and that it does not show signs of life on the planet. But the Venus transit will be used to test whether this technique will have a chance of detecting the very faint fingerprints of an Earth-like planet, even one that might be habitable for life, outside our solar system that similarly transits its own star.

Venus is an excellent stand in for Earth because of how similar in size and mass it is to our planet.

Several different instruments on Hubble will be used in this special observation. The Advanced Camera for Surveys, Wide Field Camera 3, and Space Telescope Imaging Spectrograph, to view the transit in a range of wavelengths, from ultraviolet to near-infrared light. During the transit, Hubble will snap images and perform spectroscopy, dividing the sunlight into its constituent colors, which could yield information about the makeup of Venus’s atmosphere.

Hubble will observe the Moon for seven hours, before, during, and after the transit so the astronomers can compare the data. Astronomers need the long observation because they are looking for extremely faint spectral signatures. Only 1/100,000th of the sunlight will filter through Venus’s atmosphere and be reflected off the Moon.

Because the astronomers only have one shot at observing the transit, they had to carefully plan how the study would be carried out. Part of their planning included the test observations of the Moon, such as when they took the top image of Tycho Crater.

Hubble will need to be locked onto the same location on the Moon for more than seven hours, the transit’s duration. For roughly 40 minutes of each 96-minute orbit of Hubble around the Earth, the Earth occults Hubble’s view of the Moon. So, during the test observations, the astronomers wanted to make sure they could point Hubble to precisely the same target area.

This is the last time this century sky watchers can view Venus passing in front of the Sun. The next transit won’t happen until 2117. Venus transits occur in pairs, separated by eight years. The last event was witnessed in 2004.

Find more on how you can observe the Venus transit for yourself in this article by Tammy Plotner.

Source: HubbleSite

May 4, 2012December 23, 2015 by Nancy Atkinson

Moon Craters 3-D!

A young unnamed crater on the Moon west of Isaev crater. Credit: NASA/GSFC/Arizona State University; Anaglyph by Nathanial Burton-Bradford.

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While many are hoping to see a larger-than-usual view of the Moon this weekend, here’s some great 3-D closeups courtesy of the Lunar Reconnaissance Orbiter and imaging wizard Nathanial Burton Bradford. This great 3-D view (Red/Cyan glasses needed) shows quite an interesting young impact crater on the Moon, (17.682°S, 144.408°E) west of Isaev crater. Click on the image for a larger view, and in 3-D you can dive right in and see all the nooks and crannies – what scientists call complex crater morphology.

Below you can view a Digital Terrain Model, or DTM of this same crater, and find the specifics of how deep the various parts of the crater are and other information critical to scientific investigations of the Moon.

Another recent view released by the LRO camera team is of impact melt deposit on another unnamed crater on nearside highlands (38.112°N, 53.052°E; northeast of Mare Tranquillitatis). Again, Nathanial Burton-Bradford provides a 3-D view, and amazingly, the crater walls appear deceptively steep in 3-D as opposed to the regular 2-D view:

3d_impact_melt__crater_rim_near_side_by_nathanial_bb-d4yj6l4 — 3D anaglyph of rim impact melt deposit on Unnamed crater on nearside highlands (38.112°N, 53.052°E; northeast of Mare Tranquillitatis). Credit: NASA/GSFC/Arizona State University; anaglyph by Nathanial Burton-Bradford.

What is impact melt? “So much energy is released when an asteroid or comet slams into the Moon that some of target rock (the Moon) is melted,” wrote Lillian Ostrach on the LRCO website. “For large craters, such as Tycho or Copernicus, the impact event responsible for forming these craters was large enough to generate melt that coated and covered the crater floor, and ejected melt pooled and flowed outside the crater cavity.”

Ostrach says that LROC images show that impact melt is widespread and quite common to lunar impact craters — but as this image shows – take a close look to find channels, flows, and veneers across much of the region.

Here’s LROC’s regular view:

M170205366LE_new — Impact melt started to flow back into the crater cavity before it solidified. Image width is 500 m, from the LROC Narrow Angle Camera. Credit: NASA/GSFC/Arizona State University.

Find out more about these recent LRO images on the LROC website, and see more of Nathanial’s photography handiwork at his DeviantArt page.

May 4, 2012December 23, 2015 by Jason Major

Exploration at its Finest: Cassini Visits Dione

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After completing its most recent flyby of Enceladus, Cassini made a pass by Dione — its final visit of the icy moon for the next three years. Coming within 5,000 miles (8000 km) of Dione on May 2, Cassini captured some fantastic images of the moon’s heavily-cratered and frozen surface. Here’s just a few of the raw images that arrived back here on Earth earlier today:

W00074059 — Crescent-lit Dione, with some reflected light via Saturnshine

W00074064 — A nearly fully-lit Dione, with Saturn's rings in the background

N00186325 — Dione's extensively-cratered limb

N00186448 — Some of Dione's signature "wispy lines", bright icy faces of sheer cliffs now known to be tectonic in origin

Dione 5-2-12b IR-G-UV — A color-composite image of an ancient impact crater on the edge of Dione's Saturn-facing side - this could be from the impact that spun the moon 180 degrees. (NASA/JPL/SSI/J. Major)

698 miles (1123 km) in diameter, Dione orbits Saturn at about the same distance that the Moon orbits Earth. Its composition is two-thirds water ice, which at the incredibly cold temperatures found around Saturn behaves like rock does here on Earth.

Cassini won’t visit Dione so closely again until June 2015, after spending three years angled high out of the equatorial plane while it studies Saturn’s rings and polar regions.

As Carolyn Porco, Cassini Imaging Team Leader said today, “This is exploration at its finest. It won’t continue forever. So, enjoy it while it lasts!”

See more on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site here.

Image credits: NASA/JPL/Space Science Institute

May 3, 2012December 23, 2015 by Jason Major

Enceladus On Display In Newest Images From Cassini

Enceladus' southern ice geysers are brilliant in backlit sunlight (NASA/JPL/SSI/J. Major)

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The latest images are in from Saturn’s very own personal paparazzi, NASA’s Cassini spacecraft, fresh from its early morning flyby of the ice-spewing moon Enceladus. And, being its last closeup for the next three years, the little moon didn’t disappoint!

The image above is a composite I made from two raw images (this one and this one) assembled to show Enceladus in its crescent-lit entirety with jets in full force. The images were rotated to orient the moon’s southern pole — where the jets originate — toward the bottom.

Cassini was between 72,090 miles (116,000 km) and 90,000 miles (140,000 km) from Enceladus when these images were acquired.

This morning’s E-19 flyby completed a trio of recent close passes by Cassini of the 318-mile (511-km) -wide moon, bringing the spacecraft as low as 46 miles (74 km) above its frozen surface. The goal of the maneuver was to gather data about Enceladus’ internal mass — particularly in the region around its southern pole, where a reservoir of liquid water is thought to reside — and also to look for “hot spots” on its surface that would give more information about its overall energy distribution.

Cassini had previously discovered that Enceladus radiates a surprising amount of heat from its surface, mostly along the “tiger stripe” features — long, deep furrows (sulcae) that gouge its southern hemisphere, they are the source of the water-ice geysers.

Cassini also used the flyby opportunity to study Enceladus’ gravitational field.

By imaging the moon with backlit lighting from the Sun the highly-reflective ice particles in the jets become visible. More direct lighting reduces the jets’ visibility in images, which must be exposed for the natural light of the scene or risk “blowing out” due to Enceladus’ natural high reflectivity.

The images below are raw spacecraft downloads right from the Cassini’s imaging headquarters in Boulder, CO.

N00186286 — Enceladus' geysers in action on May 2, 2012. (NASA/JPL/SSI)

W00074053 — Enceladus sprays ice into the hazy E ring, which orbits Saturn (NASA/JPL/SSI)

Cassini also swung closely by Dione during this morning’s flyby but the images from that encounter aren’t available yet. Stay tuned to Universe Today for more postcards from Saturn!

As always, you can follow along with the ongoing Cassini mission on JPL’s dedicated site here, as well as on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site.

May 2, 2012December 23, 2015 by Nancy Atkinson

Supermoon This Weekend

A 'side by side' comparison of 4 different shots taken over the period of 30 hours before the March 19, 2011 'SuperMoon'. It shows the progression of Moon in it's orbit until the closest point. Credit: Ramiz Qureshi, from Karachi, Pakistan.

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This weekend will provide the full Moon’s closest approach of the year to Earth. On Saturday, May 5, 2012 the Moon could appear as much as 14% bigger and 30% brighter than other full Moons of 2012, according to some calculations. Will you notice it? Not if you haven’t really been paying attention, or have a reference point to compare it to other full Moons. And it certainly won’t have any adverse effects on Earth, as this closest approach happens every year — just a fact of orbital mechanics. But perhaps a great way to celebrate Cinco de Mayo is to spend the evening gazing at the Moon!

Every month, as the Moon circles the Earth in its elongated orbit, its distance from the Earth varies. This weekend, the Moon is reaching what’s known as its perigee, the closest point to Earth in its orbit. It will be about 356,953 kilometers (221,802 miles) from Earth on Saturday. Apogee — when the Moon is farthest away — varies, but is around 405,000 km (252,000 miles) away.

What is most interesting is that the timing of the perigee and full Moon is really, really close: The full moon occurs at 03:34 UTC on May 6 (11:34 p.m. EDT on May 5 )eastern and perigee follows at 03:35 UTC (11:35 p.m. EDT)

David Morrison, from NASA says “supermoon” is not an astronomical term and he confirms a supermoon has no effect on Earth, and that the change in size is hardly noticeable to the average person. If you miss it, the Moon will be very nearly as close at the next full Moon, and very nearly as close as it was at the last full Moon.

But even better is that two weeks after the “supermoon” on May 5th, the Moon will be at apogee as it lines up in front of the Sun for an amazing annular eclipse on May 20th. An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.

If you’re a photographer, take a picture of the Moon and send it to us. If we get a some good images, we’ll share them. Join our Flickr group, or send us your images by email (this means you’re giving us permission to post them). Please explain a little about it such as when you took it, the equipment you used, etc.

Here’s a video NASA put out about the Supermoon:

April 27, 2012December 23, 2015 by Jason Major

Cassini Exposes Phoebe As More Planet Than Moon

Color-composite image of Phoebe as seen by Cassini in 2009.

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Saturn’s curious moon Phoebe features a heavily-cratered shape and orbits the ringed planet backwards at a considerable distance of over 8 million miles (12.8 million km). According to recent news from the Cassini mission Phoebe may actually be a Kuiper Belt object, having more in common with planets than it does with any of Saturn’s other satellites.

132 miles (212 km) in diameter, Phoebe is the largest of Saturn’s irregular moons — a cloud of small, rocky worlds held in distant orbits at highly inclined paths. Its backwards (retrograde) motion around Saturn and dense composition are dead giveaways that it didn’t form in situ within the Saturnian system, but rather was captured at some point when it strayed too close to the gas giant.

In fact it’s now thought that Phoebe may be a remnant from the formation of the Solar System — a planetesimal — with its own unique history predating its adoption into Saturn’s extended family of moons.

“Unlike primitive bodies such as comets, Phoebe appears to have actively evolved for a time before it stalled out,” said Julie Castillo-Rogez, a planetary scientist at NASA’s Jet Propulsion Laboratory. “Objects like Phoebe are thought to have condensed very quickly. Hence, they represent building blocks of planets. They give scientists clues about what conditions were like around the time of the birth of planets and their moons.”

Although Phoebe is heavily eroded and irregularly-shaped today at one time it may have been much rounder. But an early composition of radioactive elements would have generated heat, and as it warmed it “deflated” through compression, growing denser and denser.

640120main_pia15507-43_800-600 — Map of Phoebe's surface. (NASA/JPL-Caltech/SSI/Cornel)

Now, Phoebe exhibits a similar density to Pluto — another denizen of the Kuiper Belt.

At some point Phoebe may even have had water, kept liquid by its radioactive heat. That is, until the heat faded and it froze, creating the icy surface detected by Cassini’s instruments.

Still, Cassini’s study of Saturn’s moons has provided scientists with clues to what was happening much earlier on in the Solar System. What caused Phoebe to drift inwards to be caught up in orbit around Saturn? How did it survive such a supposed shuffling of planets and other worlds did not? As Cassini continues its investigation answers — and undoubtedly even more questions — will be uncovered.

Read more on NASA’s news release here.

Image: NASA/JPL/SSI. Color composition by Gordan Ugarkovic.

April 25, 2012December 23, 2015 by Nancy Atkinson

Ancient Asteroids Kept Pelting Earth in a ‘Late-Late’ Heavy Bombardment

This is an artist’s depiction of a 10-kilometer (6-mile) diameter asteroid striking the Earth. New evidence in Australia suggests an asteroid 2 to 3 times larger than this struck Earth early in its life. Credit: Don Davis/Southwest Research Institute.

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Even though the Late Heavy Bombardment is somewhat of a controversial idea, new research has revealed this period of impacts to the Earth-Moon system may have lasted much longer than originally estimated and well into the time when early life was forming on Earth. Additionally, this “late-late” period of impacts — 3.8 billion to 2.5 billion years ago — was not for the faint of heart. Various blasts may have rivaled those that produced some of the largest craters on the Moon, and could have been larger than the dinosaur-killing impact that created the Chicxulub crater 65 million years ago.

“Our work provides a rationale that the last big impacts hit over an extended time,” said William Bottke principal investigator of the impact study team at the NASA Lunar Science Institute’s Center of Lunar Origin and Evolution (CLOE), based at the Southwest Research Institute (SwRI) in Boulder, Colorado.

The evidence for these prodigious impacts comes from bead-like impact ‘spherules’ found in millimeter- to centimeter-thick rock layers on Earth and date from the Archean period of Earth’s history, more recent than the estimated LHB period of 4.1 to 3.8 billion years ago.

“The beds speak to an intense period of bombardment of Earth,” Bottke said. “Their source long has been a mystery.”

The circles seen in the image above are all formerly molten droplets ejected into space when an asteroid struck the Earth about 2.56 billion years ago. The droplets returned to Earth and were concentrated at the base of the Reivilo layer in South Africa.

The spherules still contain substantial extraterrestrial material, such as iridium (176 parts per million), which rules out alternative sources for the spherules, such as volcanoes, according to Bruce Simonson, a geologist from the Oberlin College and Conservatory who has studied these ancient layers for decades.

The timing of these impacts also coincides with a record of large lunar craters being created more recently than 3.8-billion years ago.

At least 12 spherule beds deposited between 3.47 and 1.7 billion years ago have been found in protected areas on Earth, such as in shales deposited on the seafloor below the reach of waves.

From these beds, the team found evidence of approximately 70 impacts on Earth during this time period that were likely larger than the Chicxulub impact.

In their paper, which was published in Nature, the team created a computer model of the ancient main asteroid belt and tracked what would have happened when the orbits of the giant planets changed. They extended the work of the Nice Model, which supports the theory that Jupiter, Saturn, Uranus and Neptune formed in different orbits nearly 4.5 billion years ago and migrated to their current orbits about 4 billion years ago, triggering a solar system-wide bombardment of comets and asteroids called known as the LHB.

postlc-solar-system — This image shows a representation of how the giant planets have migrated to the current orbits, destabilizing the extension of the primordial asteroid belt closest to Mars. This drove numerous big impactors onto orbits where they could hit the terrestrial planets, though over a long enough time span that this drawn-out barrage may have lasted more than a billion years. The frequency of these impacts on Earth was enough to reproduce the known impact spherule beds. Image Courtesy David Kring, Center for Lunar Science and Exploration, and the Lunar and Planetary Institute

The new computer model shows that the innermost portion of the asteroid belt could have become destabilized, delivering numerous big impacts to Earth and Moon over longer time periods.

Have there been any previous indications about this period of impacts?

“The problem is that we have almost no Archean rocks,” Bottke told Universe Today. “The oldest terrestrial craters, Sudbury and Vredefort, are 1.85 and 2.02 billion years old. The spherule beds are our only window into impacts prior to this time.”

Also, Bottke said, the number of people who look for impact spherules is almost equally scarce. “People such as Bruce Simonson, Don Lowe, Gary Byerly, and Frank Kyte, have been carrying on a long, lonely quest to try to get people to consider the implications of their work, which are deeply profound, in my opinion,” Bottke said.

As for finding evidence of this later period of impacts on the Moon, Bottke said the problem there is the lack of solid ages for most impact events.

“This means it is difficult say anything definitive about the timing of major impacts,” Bottke said. “We are working this problem now with Michelle Kirchoff, who is counting craters on top of large lunar craters. This can be done now that we have LRO data.” (Listen to a podcast interview of Kirchoff on the 365 Days of Astronomy.)

Still, Bottke said, without using “fancy dynamics,” they can address some issues.

“Studies in the post-Apollo era suggested that the Moon has four 160-300 km craters that formed after Orientale, whose age is 3.7-3.8 billion years ago and (i.e., K/T-sized events or larger),” he said. “Crater counts from the Galileo mission and Apollo-era geologic analyses suggest at least one of these events took place near 3.2-3.5 billion years ago. If we account for the gravitational cross section of the planets, we know that for every lunar event, we should get about 20 on the Earth. So, from this argument alone, one should get a lot of big impacts on the Earth after the formation of Orientale.”

The new study fits with the available constraints about impacts on the Moon as well as finding the right distribution of spherule beds on Earth.

The best way to confirm everything, however, Bottke said, would be if more lunar rocks from various locations were available for study.

Read the team’s paper in Nature.

Further reading:
Press release from SwRI.
NLSI press release

April 24, 2012December 23, 2015 by Jason Major

Lunar Satellite Reveals Apollo 16 Remains

LROC image of the Apollo 16 site showing the Orion LM. (NASA/GSFC/Arizona State University)

NASA’s Lunar Reconnaissance Orbiter (LRO) made a low pass over the Apollo 16 site last fall, capturing images of the leftovers from John Young and Charlie Duke’s 1972 exploration of the Descartes Highlands. The video above takes us on a tour of the Apollo 16 site from lunar orbit, and includes audio from the original communications and some very nice comparative photos and video clips showing the same features from ground level.

The goal of Apollo 16 was to explore for the first time a lunar highlands location, and collect samples of what were initially thought to be volcanic rocks. The rocks were believed to be of a different material than what was collected during previous missions.

As it turned out, the rocks collected by Duke and Young weren’t volcanic in origin at all; they ended up being breccias — cemented-together chunks ejected from ancient cratering events hundreds of miles away.

Apollo 16 also set up various experiment packages to study lunar geology, magnetism and the solar wind. The Lunar Roving Vehicle (LRV) allowed Young and Duke to travel across a much wider area than they would have otherwise been able to on foot. It was the second mission to use an LRV, and the rover — as well as its tracks — are still there today, looking exactly as they did when they were left 40 years ago.

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The Apollo 16 ascent stage lifted off from the lunar surface on the evening of April 23, 1972 and docked with the Command Module containing Ken Mattingly. The following day the astronauts began their trip back to Earth, completing the 250,000-mile traverse three days later on April 27.

The Moon would be visited again in December of that same year during Apollo 17, the last mission of the program and the last time that humans would walk on the surface of another world. Now, 40 years later, satellites orbiting the Moon take pictures of what was left behind by these historic events. Perhaps someday soon the sites will be visited from ground level… maybe even by a new generation of astronauts.

Apollo16_pan — Panorama of the Descartes Highlands site made from 3 Hasselblad film image scans combined together. (NASA/JSC/J. Major)

Read more about this on Arizona State University’s LROC site, and explore the full-frame Narrow-Angle Camera image from the LROC here.

Video: NASA/GSFC/Arizona State University

April 24, 2012December 23, 2015 by Jason Major

The Family that Went to the Moon

A picture of a photograph: the family photo that Charlie Duke left on the Moon on April 23, 1972. (NASA)

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Well, the family photo, anyway.

On April 23, 1972, Apollo 16 astronauts Charlie Duke and John Young embarked on the third and final EVA of the mission, exploring the Descartes Highlands via Lunar Roving Vehicle. During the EVA, before setting up a Solar Wind Collector, Duke placed a small family photo he had brought along onto the lunar surface and snapped a few photos of it with his Hasselblad film camera. This is one of the photos.

The portrait shows Charlie, his wife Dorothy, and their two sons Charles and Thomas. It looks like they are sitting on a bench in the summertime.

The family photo, gingerly wrapped in clear plastic and slightly crumpled from being stashed in the pocket of a space suit, was left on the Moon. It presumably still sits there today, just inches away from Charlie’s boot print — which, presumably, is also there.

At the time of this writing it’s been exactly 40 years to the day that this photo was taken.

Image: NASA/JSC scan

I came across this image while looking through the Project Apollo Image Archive for some relevant images from the Apollo 16 mission. Amid scans of Hasselblad photos showing lunar samples, experiments and scenes from LRV jaunts, which are all fascinating in their own right, I came across this poignant image and couldn’t resist sharing it. To know that a family photo is resting upon the surface of another world is nothing short of amazing… while the missions to the Moon were a testament to human endeavor, it’s small things like this that remind us of the people that made it all possible.

April 23, 2012December 23, 2015 by Nancy Atkinson

Join the Million Crater Challenge

Like a challenge? Right now you can join in a contest to mark a million craters, as part of the Moon Mappers project. “Our challenge to you is to try and observe 1 million craters on the Moon before the full Moon again rises in the evening sky on May 5,” said Dr. Pamela Gay, who leads the Cosmoquest program of citizen science project. “Help us ‘illuminate’ the Moon with new scientific discoveries one crater at a time.”

As an enticement to join in, there are prizes!

There will be prizes for the ten CosmoQuest community members who make the observations closest to each interval of 100,000, and for 10 additional randomly selected community members who participate in this challenge. Prizes include Surly Amy pendants, Astrosphere posters, and Lunar Reconnaissance Orbiter lithographs.

Are there a million craters on the Moon? Dr. Gay said that with LRO, craters the size on 1 meter can be seen. But for Moon Mappers, participants are asked to identify craters nine meters in diameter. “There are literally millions of craters at that size,” she said.

Moon Mappers is not only fun, but your contributions help build a new scientific understanding of the Moon. The Moon Mappers team has already published their first scientific paper based on the work done by citizen scientists, so help them keep going to discover as much as we can about the Moon.

Check out Moon Mappers!