Photographs of Kilauea Lava Flows

I found these while researching the caption for a satellite image of lava flowing into the ocean on Hawaii’s Big Island. Large versions (and more photos) on the USGS Kilauea Images site.

Glowing lava visible through a skylight on the Pulama pali (steep hill/cliff), Hawaii.

Exploding lava at the Puhi-o-Kalaikini ocean entry.

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Odds & Ends: Earth from the Moon

North and South America, August 9, 2010.

Lunar Reconnaissance Orbiter Camera. NASA/GSFC/Arizona State University.

Full Caption

By Mark Robinson, LROC Team.

As LRO orbits the Moon every two hours sending down a stream of science data, it is easy to forget how close the Moon is to the Earth. The average distance between the two heavenly bodies is just 384,399 km (238,854 miles). Check your airline frequent flyer totals, perhaps you have already flown the distance to the Moon and back on a single airline!

LROC’s most recent Earth calibration sequence captured a magnificent view of the Americas with only minimal cloud cover. Contrast the current image with the NAC view taken last June, which revealed much of central Asia.

The Moon is a spectacular sight in the nighttime sky. Now imagine the Earth from the Moon, four times larger, a delicate blue, and it does not rise nor set. To astronauts, the Earth is a constant companion, at least on the nearside. Of course, on the farside you can never see the Earth.

The overarching goal of the LRO mission is to obtain the data needed to enable engineers and scientists to design the hardware and instruments to pick up lunar exploration where it was paused in December of 1972, after Apollo 17. LRO has now collected these data, so we are ready to move along the path of returning to the Moon! Will designs for lunar habitats include Earth windows? Certainly a human factor to consider! Are there any adverse psychological effects for future lunar explorers on the farside with no Earth overhead? What do you think? For now, we are happy to occasionally snap an image of the Earth as the NAC collects routine calibration data.

View the full-size image (4400 by 440 pixels) on the LROC gallery.

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Time Lapse of San Francisco Fog

A little bit off topic, but worth it. Time lapse photography of clouds & fog in the Bay Area. Watch to the end, it’s worth it. From the Mother Jones Blue Marble blog.

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Odds & Ends: Dust over the Taklamakan Desert

An astronaut took this photograph of dust obscuring the Taklamakan Desert, with the Tien Shan mountains in the distance, on September 5, 2010.

Astronaut photograph ISS024-E-13439.

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G. Projector

In the comments to my Natural Earth post Jim Meyer suggested I make copies of the global maps centered on the Poles. Rather than just making a few images I’ll mention G.Projector: the simplest map projection conversion software I know of. Developed by NASA Goddard Institute of Space Studies, it features 93 map projections, (assuming I didn’t lose count) decent customization options, and a good coastline database at multiple resolutions. Even better, it’s free.

The conversion process is straightforward: import an image in the equirectangualr map projection, pick a new projection, set options for coastlines and other overlays, then export. Very, very, simple (in contrast to many other remapping applications which seem to be written for people with GIS degrees). Here’s some examples:

North Pole, Orthographic Projection

North Pole, stereographic projection to 45° North.

South Pole, stereographic projection to 60° South.

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Devils Lake Interactive

The associated press took a pair of our satellite images (Devils Lake, North Dakota) and made a nice little tool to interactively sweep between the pictures acquired in 1984 and 2009: Expanding North Dakota lake swallows land and buildings. I think it works quite a bit better than stacked images, or a simply flipping between the two with a mouse rollover or button press.

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Design Basics: Anti-Aliasing

One of the simplest ways to improve the look of graphics on a computer screen is to anti-alias them: i.e. smooth any curved or angled edges. At the relatively low resolution of a computer screen (nominally 72 dots per inch, although modern screens are often around 100 dots per inch) it’s easy to spot blocky pixels along any sharp edge that’s not perfectly vertical or horizontal. Here’s an example:

Aliased vs. anti-aliased text.

Most modern graphics software anti-aliases by default (and modern operating systems anti-alias text on the desktop, in browsers, and other applications), so text & graphics usually look pretty good. Unfortunately, a lot of scientific visualization software doesn’t (at least not by default)—so many of the graphics NASA produces (especially those that are generated automatically as data is processed) look chunky. Like this:

Default output from ENVI.

One quick fix is just to render out any graphic larger than it needs to be (4 times is fine) and shrink it using a resampling algorithm like bilinear or bicubic that blends pixels [nearest neighbor (also the default in many visualization packages) will not]. If your data has a vector overlay it’s often feasible to export a Postscript file, and then render the image in something like Illustrator, which will produce nice smooth lines:

Map exported from ENVI as postscript, then imported and rasterized in Illustrator.

As always in design there are exceptions and caveats. Horizontal and vertical lines, like the axes on a graph, look much better when they’re sharp, and anti-aliasing can blur them. I usually export any elements of a graphic that need to be as sharp as possible as a separate step, with anti-aliasing turned off. Likewise, printed material should not be anti-aliased. Most printers are high-enough resolution that curved edges look perfectly clean.

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Odds & Ends: The Milky Way

While poking around the Gateway to Astronaut Photography of Earth (tens of thousands of photos of Earth from space, dating back to the Mercury program) I found this photo of the Milky Way rising (setting?) above the Earth’s limb:

Astronaut Photograph STS131-E-14516

Taken from the Space Shuttle Discovery on April 18, 2010.

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Odds & Ends: Mount St. Helens

Really busy this week, so I’ll just post this slightly off-center satellite view of Mount St. Helens:

Mount St. Helens, August 23, 2010.

Click for the large version, and be sure to check out Devastation and Recovery at Mt. St. Helens to see the volcano and its surroundings every year from 1979 to 2009, including the immediate aftermath of the 1980 eruption. 2010 coming soon. (Image acquired by the Advanced Land Imager on board Earth Observing-1 on August 23, 2010.)

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Natural Earth

We just published a mini-feature on the recent forest fires in Russia—Russian Firestorm: Finding a Fire Cloud from Space—accompanied by this map of smoke movement (read the article for details, then come back):

I’m reasonably happy with the map, largely due to the wonderful Natural Earth data I used as a base. Put together by Nathaniel Vaughn Kelso, Tom Patterson, and many others. It uses NASA’s Blue Marble imagery, but it’s lightened and desaturated, which works much better than the Blue Marble when combined with other data. The maps based on color imagery are complemented by another set: “Cross-blended Hypsometric Tints”. These are based on elevation data (SRTM 30 plus), but have the added twist that arid and temperate climates get separate color palettes, so deserts look like deserts and forested areas are green.

Natural Earth

Cross-blended Hypsometric Tints

If that weren’t enough (I’m beginning to sound like a salesman) there’s a matching set of vector (resolution-independent) data for coastlines, country boundaries, rivers, roads, etc., optimized for three different scales (a low-resolution map needs less-detailed coastline data than a high-resolution map, otherwise areas of coastline with fine detail become a blobby mess). If you make maps, or even just like maps, they’re well worth checking out.

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