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From a press release originally published on the John Hopkins Laboratory website on October 15, 2015.

Following the first exploration of the Pluto system in history, NASA’s New Horizons team have published their first research paper detailing their findings of the distant planet.

The paper, entitled “The Pluto System: Initial Results from its Exploration by New Horizons,” describes an unusual heart-shaped region, intriguing moons, and a surprising degree of diversity and complexity in the Pluto System.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Team members believe that some of the processes on Pluto have occurred relatively recently, including those which involve the water-ice rich crust that they have discovered. This raises fundamental questions about how small planets remain active billions of years after their formation.

NASA’s New Horizons spacecraft made it to within 7,750 miles of Pluto’s surface at its point of closest approach, gathering so much data that scientists won’t see the extent of it for another year.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Jim Green, director of planetary science at NASA Headquarters in Washington, describes the mission as only the beginning. “The New Horizons mission completes our initial reconnaissance of the solar system, giving humanity our first look at this fascinating world and its system of moons. New Horizons is not only writing the textbook on the Pluto system, it’s serving to inspire current and future generations to keep exploring — to keep searching for what’s beyond the next hill.”

For more information on what we know so far about the dwarf planet right on the fringes of our Solar system, see Chapter 8.1 of The Cosmos.

Link: for the original press release, click here.

In this NY Times slideshow, Kenneth Chang curates a selection of images from NASA’s Cassini spacecraft’s farewell tour. Cassini entered orbit around Saturn 11 years ago; last fall, the space agency granted a final extension, through 2017, when the spacecraft will have exhausted the fuel for its thrusters. On August 17, it made its last flyby of Dione, the fourth largest of Saturn’s more than 60 moons, at 700 miles wide. Dione has its own mysteries that planetary scientists hope to unravel.

See the slideshow here (external link).

From APOD, June 3, 2105:

A new view of Saturn’s moon Hyperion was released by the Cassini team during a recent fly-by.


Credit: NASA/JPL-Caltech/SSI

The images shows numerous unusually-shaped craters with dark material at the bottom. At around 250 km across, its gravitational pull on Cassini reveals that it is mostly empty space. The unusual crater shapes are thought to arise from surface impacts, which compress and eject surface material, unlike the regular circular shock-wave craters seen on other moons and planets.

Link: APOD, June 3, 2015.

From a news report on, April 20, 2015:

The Japan Aerospace Exploration Agency (JAXA) has unveiled the plan for a Moon lander. If successful, Japan will be the fourth country to send an unmanned probe to the moon after Russia, the United States, and China.

JAXA plans to launch the mission as early as 2018, with a development cost estimated at up to 15 billion yen ($126 million). The probe, named SLIM (Smart Lander for Investigating Moon), will be carried by the nation’s solid-fuel “Epsilon” rocket.

Link: article.

From an article on CNET by Michelle Starr, February 12, 2015; visualizations by Ernie Wright:

As the Moon orbits the Earth, we only ever see the one side. This is because the moon is tidally locked – a single rotation of its axis takes the same amount of time as a single orbit around the Earth, so that the same side is always facing the Earth. Using its Lunar Reconnaissance Orbiter, NASA has collated data to reveal what the other side of the Moon looks like (see Section 6.2a, p. 127 and Figure 6-18, p. 133).


Credit: NASA’s Goddard SFC Scientific Visualization Studio

As the Moon goes through its phases, we see it darken and lighten as viewed from Earth. Those phases are the opposite of what the far side of the Moon experiences: when we have a Full Moon, the far side is new; when we have a New Moon, the far side is full. This means that the LRO can observe the far side of the Moon in pretty good detail when it is illuminated by the Sun.

In the years since it launched in 2009, the LRO has sent back hundreds of terabytes of data about the Moon’s far side. What it has found is that the far side of the Moon is quite different from the side we see.

Links: CNET article; more information from NASA’s Scientific Visualization Studio; LRO home.

Abridged from a New Scientist article by Rebecca Boyle, September 30, 2014:

A newly discovered asteroid called 2014 OL339 is the latest quasi-satellite of Earth – a space rock that orbits the Sun but is close enough to Earth to look like a companion. The asteroid has been hanging out near Earth for about 775 years, but its orbit is unstable – it will probably move on about 165 years from now.

Credit: NASA

Credit: NASA

Quasi-satellites orbit in resonance with Earth, allowing our planet’s gravity to shift the rock’s position. The asteroid orbits the Sun every 365 days, as Earth does, but Earth’s gravity guides it into an eccentric wobble, which causes the rock to appear to circle backward around the planet.

The asteroid, which is between 90 and 200 metres in diameter, is among several different categories of space rock in Earth’s retinue besides our one satellite, the Moon. Rocks that hang out at a gravitational middle ground known as a Lagrange point, where they follow or lead Earth in its orbit, are called Trojans.

Links: The full New Scientist article; NASA’s Near-Earth Object program.

From a JPL press release dated November 21, 2014:

Scientists have produced a new version of what is perhaps NASA’s best view of Jupiter’s ice-covered moon, Europa. The mosaic of color images was obtained in the late 1990s by NASA’s Galileo spacecraft. This is the first time that NASA is publishing a version of the scene produced using modern image processing techniques.

Credit: NASA/JPL-Caltech/SETI Institute

Credit: NASA/JPL-Caltech/SETI Institute

The new image more closely approximates what the human eye would see than the earlier version (released in 2001). The image features many long, curving and linear fractures in the moon’s bright ice shell. Scientists are eager to learn if the reddish-brown fractures, and other markings spattered across the surface, contain clues about the geological history of Europa and the chemistry of the global ocean that is thought to exist beneath the ice.

In addition to the newly processed image, a new video details why this likely ocean world is a high priority for future exploration.

Links: more details about the image above; Europa exploration movie; NASA’s Europa homepage.

An uncrewed Chinese lunar probe was launched on October 23, 2014, to fly around the Moon and back to Earth, in an 8-day mission. Called Chang’e 5-T1, it was a test mission in advance of the Chinese 2017 Chang’e 5 mission that is planned to return lunar rocks and soil to Earth. The return capsule of Chang’e 5-T1 landed in Inner Mongolia, on October 31, 2014.
Chang'e 5T1


Like its predecessors, the spacecraft is named after the Chinese Moon goddess Chang’e.
Links: report on

From a NASA press release, April 18, 2014:

Ground controllers at NASA’s Ames Research Center in Moffett Field, California, have confirmed that NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft impacted the surface of the Moon, as planned, on Thursday, April 17. LADEE lacked fuel to maintain a long-term lunar orbit or continue science operations and was intentionally sent into the lunar surface. The spacecraft’s orbit naturally decayed following the mission’s final low-altitude science phase. (See p. 135.)

Credit: NASA

During impact, engineers believe the LADEE spacecraft, the size of a vending machine, broke apart, with most of the spacecraft’s material heating up several hundred degrees – or even vaporizing – at the surface. Any material that remained is likely buried in shallow craters. At the time of impact, LADEE was traveling at a speed of 3,600 miles per hour.

In early April, the spacecraft was commanded to carry out maneuvers that would lower its closest approach to the lunar surface. The new orbit brought LADEE to altitudes below one mile (two kilometers) above the lunar surface. This is lower than most commercial airliners fly above Earth, enabling scientists to gather unprecedented science measurements.

In the coming months, mission controllers will determine the exact time and location of LADEE’s impact and work with the agency’s Lunar Reconnaissance Orbiter (LRO) team to possibly capture an image of the impact site. A thorough understanding of the characteristics of our nearest celestial neighbor will help researchers understand other bodies in the solar system, such as large asteroids, Mercury and the moons of outer planets.

Links: full NASA press release; NY Times article; LADEE mission homepage.

The opening sentence misstates the size of Triton relative to our Moon. The sentence should read:

“Neptune’s largest moon, Triton, is slightly smaller than our Moon and has a retrograde (backward) orbit.”

The pictorial chart on pp. 228-229 and the accompanying table on p. 230 give the correct size order.