A Moon with Weather and Erosion

titan_cratersTitan is the only moon in the solar system with a thick atmosphere, and the only world besides Earth known to have lakes and seas on its surface. However, with a frigid surface temperature of around -290° F (94 K), the rain falling on Titan isn’t water. It’s liquid methane and ethane, compounds that are gases at room temperature on Earth.

Most of Saturn’s moons display their ancient faces pockmarked by thousands of craters. Titan, Saturn’s largest moon, looks younger than it really is because its craters are being eroded. Radar observations by the Cassini spacecraft show that dunes of hydrocarbon sand are filling in the craters.

This image taken with the Cassini radar shows two craters on Titan. On the left is crater Sinlap which is a relatively ‘fresh’ crater, with a depth-to-diameter ratio similar to is found on other large moons in the solar system such as Ganymede. One the right is Soi, an extremely eroded crater with a very small depth compared to similar craters on Ganymede. These craters are both about 80 km (almost 50 miles) in diameter.

Image Credit: NASA

Titan and Tethys

converted PNM fileSaturn’s moon Tethys with its prominent Odysseus Crater seems to lurk behind Saturn’s largest moon Titan in this image taken by the Cassini spacecraft in 2014.

The Titans were the pre-Olympian gods in Greek mythology. Tethys was a Titan daughter of Uranus and Gaia, sister and wife of the Titan Oceanus, and mother of the river gods and the Oceanids

Image Credit: NASA

The Dust Storms of Titan

Analysis of data taken by the Cassini spacecraft appears to show giant dust storms on Saturn’s moon Titan. Titian is the second largest moon in the Solar System (Jupiter’s moon Ganymede is slightly bigger.); it’s even lager than the planets Mercury and Pluto (Pluto is still a planet in the Hogewash! universe.). Titan is the only other body in the Solar System beside Earth that has stable surface liquid, hydrocarbons rather than water. If the dust storms are really occurring, it would join Earth and Mars as the only known bodies in the Solar System with dust storms.

The animation above is based on images captured by Cassini mission during several Titan flybys in 2009 and 2010. The bright spots that have been interpreted as evidence of the dust storms.

There’s more information about this at the NASA website.

Image Credit: NASA

Not a Solar Eclipse

titanbusy_cassini_960No, it’s not a solar eclipse. It’s a picture of the rings and a couple of the moons of Saturn. The large object near the center is Titan, Saturn’s largest moon and one of the most interesting objects in the entire Solar System. The central dark spot is the body of the moon. The bright halo is atmospheric haze above Titan. The gases of the atmosphere scatter sunlight. Saturn’s rings are shown nearly edge on. Enceladus, a small moon, is at about 4 or 5 o’clock at the edge of Titan.

This image was taken with the Cassini spacecraft’s camera pointing almost directly at the Sun, so the surfaces of Titan and Enceladus appear in silhouette, and the rings of Saturn look like a photographic negative.

Image Credit: NASA

A Reflection from Titan

titan_lake_flashThis image shows a flash of sunlight reflected off a lake on Titan, Saturn’s largest moon. Its northern hemisphere is shrouded in darkness for nearly 15 years, but the sun begins to illuminate the area again as it approaches its spring equinox. The Cassini spacecraft was able to detect the glint at the beginning of Titan’s spring in 2009. The moon’s hazy atmosphere scatters and absorbs many wavelengths of light, including most of the visible spectrum. But an onboard instrument was able to detect the glint in infrared wavelengths that can penetrate through Titan’s atmosphere. This image was created using wavelengths of light in the 5 µm range.

Image Credit: NASA

Broken Rings?

broken ringsThat’s not a gap in Saturn’s rings. It’s the planet’s shadow. During most of Saturn’s year, the planet’s shadow extends well beyond the edge of the rings.  However, with summer solstice fast approaching, the Sun is higher in Saturn’s sky and most of Saturn’s A ring is completely shadow-free.

Saturn’s large moon Titan, its northern hemisphere in sunlight of late spring, hangs above the rings.

Image Credit: NASA

The Mystery of Ligeia Mare

Titan Mare FeaturesThe images above were taken by the Radar instrument aboard the Cassini spacecraft. They show the evolution of a changing feature in the large hydrocarbon sea named Ligeia Mare on Saturn’s moon Titan. The small images in the column at left show the same region of Ligeia Mare as seen by Cassini‘s radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015.

Analysis suggests that the changes in the bright features are cause by either waves, solids at or beneath the surface, or bubbles. Waves are generally thought to be the most likely explanation, but tides or sea level and seafloor changes might be the cause.

The large image panel shows all of Ligeia Mare which is Titan’s second-largest liquid hydrocarbon sea and has a total area of about 130,000 square km, making it 50 percent larger than Lake Superior on Earth.

Image Credit:NASA

Seasons on Titan

Titan TemperaturesThis animated sequence of maps shows varying surface temperatures on Saturn’s moon Titan at two-year intervals from 2004 to 2016. The measurements were made by the Cassini spacecraft. They show heat coming from Titan’s surface at a wavelength of 19 µm, a wavelength at which the moon’s otherwise opaque atmosphere is somewhat transparent. Temperatures have been averaged around the globe from east to west to emphasize the seasonal variation across latitudes. Regions for which there are no data show up as black.

Titan’s surface temperature changes slowly over the course of the Saturn system’s long seasons, which each last 7-1/2 years each. As on Earth, the amount of sunlight received at any location changes as the Sun appears to move north or south in Titan’s sky over the course of the 30-year-long Saturnian year. Cassini arrived at Saturn in 2004 when Titan’s southern hemisphere was in late summer and was the moon’s warmest region. By 2010, shortly after the 2009 equinox, temperatures were about the same across the northern and southern hemispheres, similar to the situation seen by Voyager 1 in 1980, one Titan year earlier.

Image Credit: NASA

The Surface of Titan

Titian in IRThis composite image was stitched together using infrared views of Saturn’s moon Titan taken by the Cassini spacecraft. They were acquired during the a flyby on last month. The spacecraft’s visual and infrared mapping spectrometer (VIMS) instrument took the pictures. In this false color image blue represents wavelengths centered at 1.3 µm, green represents 2.0 µm, and red represents 5.0 µm. Visible light centered around 0.5µm reveals nothing below Titan’s hazy atmosphere. The near-infrared wavelengths in this image allow Cassini’s vision to penetrate the haze.

Image Credit: NASA

Triple Crescent

Triple CrescentSaturn has many moons. The three shown here—Titan, Mimas, and Rhea—show marked contrasts in their surface features. Titan, Saturn’s largest moon and the largest moon in this image, appears fuzzy because we only see its clouds. Because Titan’s atmosphere refracts light around the moon, its crescent is wrapped just a little further around the moon than it would on an airless body. Rhea (upper left) appears rough because its icy surface is heavily cratered. A close inspection of Mimas, though difficult to see at this scale, would show surface irregularities because of its violent history.

Image Credit: NASA

One more thing … If it’s clear where you are this evening, go outside and look up in the western sky just after sunset. There’s a conjunction of Venus and Jupiter tonight. They will be separated by less than half the diameter of the Full Moon.

Titan—the Hard Way

Six Nightly Views of Titan's SurfaceWe’re used to seeing pictures of Saturn’s moon Titan taken by the Cassini spacecraft. These views of Titan were taken by a ground-base telescope, the Very Large Telescope at the European Southern Observatory in Chile. The image on the right has been enlarged for clarity, and the coordinate grid used Titan overlaid. The images are false-colour renderings coded with red (1.575 μm; surface), green (1.600 μm; surface), and blue (1.625 μm; atmosphere), respectively.

Image Credit: ESO