Looking at Neptune

Neptune-This picture of Neptune was produced from the last whole planet images taken through the green and orange filters on the Voyager 2 narrow angle camera. The images were taken on 31 years ago at a range of about 7 million km, 4 days and 20 hours before closest approach on 25 August, 1989. The picture shows the Great Dark Spot and its companion bright smudge. The fast moving bright feature called “Scooter” and the little dark spot are visible near the western limb. These clouds were seen to persist for as long as Voyager‘s cameras could resolve them. A bright cloud band similar to the south polar streak may be seen to the north.

Six years ago, the New Horizons spacecraft crossed the orbit of Neptune today on its way to Pluto, but Neptune was not nearby. In July,2014, New Horizons took this picture of Neptune from almost 4 billion km away.neptune-triton-7-10-14-new_hoizonsImage Credit: NASA

The Kuiper Belt Object Formerly Known as Ultima Thule

New Horizons images of the Kuiper Belt Object Arrokoth taken from many angles have been used to determine its 3D shape, providing insight into the KBO’s origins. The flattened shapes of the two lobes and the tight alignment of their poles and equators are evidence an orderly, gentle merger of two objects forming from the same cloud of particles. Arrokoth appears to have come together slowly, growing from “locally-sourced” materials found in a small part of the early solar nebula. Such an object would not have formed in a more chaotic accretion environment.

Video Credit: NASA / JHUAPL / SWRI / James Tuttle Keane

The Far Side of Pluto

nh-pluto-atmosphere-infraredThis image from the New Horizons spacecraft was our first look at Pluto’s atmosphere in infrared wavelengths. The planet is backlit with sunlight coming from above and behind. The image was captured captured just after the flyby on 14 July, 2015, while New Horizons was about 180,000 km beyond Pluto. The false color image codes wavelengths around 1.25 µm as blue, 2.5 µm as red, and intermediate wavelengths as green. North in this image is at roughly 10 o’clock.

The blue band is the result of sunlight being scattered by haze particles in the planet’s atmosphere, haze which is suspected of being photochemical smog caused by the action of sunlight on methane and other molecules. These form hydrocarbons such as acetylene and ethylene which accumulate into small particles. The µm-sized scatter sunlight giving the haze its blue tint. It looks blue in visible light too. No SUVs were detected during the flyby, so this is likely a natural process. Note that Pluto is moving further from the Sun for the next century or so (it’s orbit is highly eccentric), so it is experiencing global cooling.

The whitish patches around Pluto’s limb are from sunlight bouncing off more reflective or smoother areas on its surface.

Image Credit: NASA

Ultima Thule in Color

This composite image of Kuiper Belt Object 2014 MU69 (aka Ultima Thule) isfeatured on the cover of the May, 2017 issue of the journal Science. It was compiled from data obtained by the New Horizons spacecraft as it flew by Ultima Thule on New Years Day. The image combines color data with detailed high-resolution panchromatic pictures to present the view as the human I would see it.

Image Credits: NASA / JHUAPL ./ SWRI / Roman Tkachenko

The Shape of Ultima Thule

Here’s NASA’s description of this brief video: This animation depicts a shape model of Ultima Thule created by the New Horizons science team based on its analysis of all the pre-flyby images sent to Earth so far. The first half of the movie mimics the view from the New Horizons spacecraft as it approached Ultima Thule and has the “snowman” shape that was so frequently mentioned in the days surrounding the New Year’s 2019 flyby. The movie then rotates to a side-view that illustrates what New Horizons might have seen had its cameras been pointing toward Ultima Thule only a few minutes after closest approach. While that wasn’t the case, mission scientists have been able to piece together a model of this side-view, which has been at least partially confirmed by a set of crescent images of Ultima Thule (link). There is still considerable uncertainty in the sizes of “Ultima” (the larger section, or lobe) and “Thule” (the smaller) in the vertical dimension, but it’s now clear that Ultima looks more like a pancake than a sphere, and that Thule is also very non-spherical. The rotation in this animation is not the object’s actual rotation, but is used purely to illustrate its shape.

Video Credit: NASA / JHU APL / SWRI

Ultima Thule in the Rear View Mirror

This animation was assembled from images taken by the New Horizons Long Range Reconnaissance Imager after the spacecraft flew past Ultima Thule on New Year’s Day. The central frame of the sequence was taken on at 05:42:42 UT when the spacecraft was 8,862 km past the Kuiper Belt Object and 6.6 billion km from Earth. The KBO’s illuminated crescent is blurred in the individual frames because long exposure times were required boost the camera’s signal level. The Sun’s light is roughly 2000X dimmer at Ultima Thule that here on Earth. This is the farthest movie of any object in our Solar System ever made by a spacecraft.

Image Credits: NASA / JHUAPL / SWRI / NOAO

Lots Moar Pixels!

Better resolutions pictures of Ultima Thule are now coming in from New Horizons. We can now tell that it’s a two-lob object, and the mission science team has named the two lobes “Ultima” and “Thule.”

There are about 28,000 pixels across this image of Ultima Thule. The image I posted yesterday contained 6 pixels.

Color data from the low-resolution camera has been overlaid with higher resolution imagery to produce this first color image.More data will be coming in over the coming weeks.

Stay tuned.

Ultima Thule in 2 Pixels

The New Horizons spacecraft took this picture of Ultima Thule as part the last check on its flyby trajectory. The image on left is the the raw data. The KBO is so small that it only occupies two pixels. The image on the right is a processed version that show gives a general view of its shape. Ultima Thule is far enough away that radio signals take a bit over six hours to travel to Earth. As I’m posting this, the first flyby data has just been received.

Stay tuned.

Image Credit: NASA

Ultima Thule Flyby Update

The New Horizons team at Johns Hopkins University Applied Physics Laboratory has been busy preparing for the spacecraft’s flyby of the Kuiper Belt Object nicknamed Ultima Thule on New Year’s Day. This update was posted on 28 December.

Video Credit: JHUAPL

BTW, Mrs Hoge and I met Alan Stern at a sushi bar in Columbia, Maryland, several years before New Horizons launched. We had been to a medical appointment and stopped for lunch, and he sat down a few seats down the bar from us. In the course of our  conversation, I found out that he was in the area to pitch the idea of the Pluto flyby mission to NASA, and I’ve been following the project’s progress ever since.

The Ultima Thule Flyby

Ultima Thule is a nickname for the Kuiper Belt Object known as 2104 MU69. The picture above is an overlay of 5 images taken by the Hubble Space Telescope. The images were taken at 10-minute intervals on 24 June, 2014. The positions of 2014 MU69 in the images are shown by the green circles.

On New Year’s Day, 2019, the New Horizons spacecraft will fly by Ultima Thule. The science objectives of the flyby include imaging the KBO to determine its shape, geology, and surface composition. The surrounding environment will be scanned to detect any possible moons, coma, or rings.

New Horizons made its first detection of 2014 MU69 on 16 August, 2018, at a distance 172 million km. At that time, 2014 MU69 appeared as a magnitude 20 object from New Horizon‘s point of view. It won’t appear at naked eye brightness (magnitude 6) until the spacecraft is within 3 to 4 hours of closest approach.

Image Credit: NASA / ESA

New Horizon’s First Glimpse of Ultima Thule

The New Horizons spacecraft has caught its first glimpse of its next flyby target, the Kuiper Belt object nicknamed Ultima Thule, a bit more than four months ahead of its New Year’s Day close encounter. The image on the left is a composite produced by adding 48 different exposures from the News Horizons Long Range Reconnaissance Imager (LORRI), each with an exposure time of 29.967 seconds. They were taken on 16 August. The predicted position of Ultima Thule is at the center of the yellow box as indicated by the crosshairs. It’s just above and left of a nearby star that is approximately 17 times brighter than Ultima Thule. On the right is a magnified view of the yellow box that has been processed by subtracting the background star field a recorded by LORRI in September, 2017, well before before it could detect the Ultima Thule itself. The small Kuiper Belt Object is clearly visible in this star-subtracted image and is very close to where the mission navigation team predicted, indicating that New Horizons is on course.

The many artifacts in the star-subtracted image are caused either by small mis-registrations between the new LORRI images and the template or by intrinsic brightness variations of the stars. At the time of these observations, Ultima Thule was was roughly 6.5 billion km from the Sun, and New Horizons was around 172 million km from Ultima Thule.

Image Credits: NASA / JHUAPL / SwRI


Nix is one of Pluto’s small moons. It was discovered using the Hubble Space Telescope in 2005. It was the best imaged of the small moons by the New Horizons spacecraft during the 2015 flyby of Pluto. This is the highest-resolution image of Nix. On 14 July, 2015, the basic image was captured in grayscale by LORRI camera and color has been added based on other images from Ralph MVIC.

Image Credit: NASA

Kuiper Belt Objects

The New Horizons spacecraft has recently observed several Kuiper Belt objects (KBOs) using its Long Range Reconnaissance Imager (LORRI). These December, 2017, false-color images of KBOs 2012 HZ84 (left) and 2012 HE85 are, for now, the farthest images from Earth ever captured by a spacecraft. It’s now even farther out than Voyager 1 was when it took the famous “Pale Blue Dot” image in which Earth shows up as a single pixel, but it will be sending back more images from even farther out. On New Year’s Day, 2019, New Horizons will fly by its next survey target, a KBO named 2014 MU69 which is over one-and-a-half billion km beyond Pluto.

Image Credit: NASA

Charon Lit by Plutoshine

This image was taken by the Ralph/Multispectral Visible Imaging Camera aboard New Horizons on 15 July, 2015, when the spacecraft was around 160,000 km beyond Pluto. It shows the night side the moon Charon against a star field. Charon, which about the size of Texas, is mostly lit by faint light reflected from Pluto. The bright crescent on Charon’s right edge is a bit of sunlit terrain, overexposed compared to the rest of the image.

Image Credits: NASA / JHUAPL / SwRI