Do you truly know our Solar System?
The hematite spheres (or ‘Martian blueberries’) as imaged by the Mars Exploration Rover. These are almost certainly evidence of past liquid water on Mars, and possibly of past life. NASA scientists must be certain that this site – and this planet – are not contaminated by the very act of our observing. As of yet, there is no surefire evidence for either past or present Martian life.
( Credit: NASA/JPL-Caltech/Cornell/Arizona State University)
Each world holds secrets that typically go unrecognized.
The northern polar aurorae seen on Jupiter, as imaged here with Hubble’s NICMOS camera, represents a cyclotron-driven maser: the first such one detected from a planetary body within our own Solar System.
( Credit: NASA, ESA, and J. Nichols (University of Leicester))
Can you identify all 10?
The surfaces of six different worlds in our Solar System, from an asteroid to the Moon to Venus, Mars, Titan and Earth, showcase a wide diversity of properties and histories. While Earth is the only world known where life arose, these other worlds may someday expand our current understanding of how frequently life arises.
( Credit: Mike Malaska; ISAS/JAXA, NASA, IKI, NASA/JPL, ESA/NASA/JPL)
1.) I’m the hottest planet.
The WISPR data from the Parker Solar Probe, in monochrome, clearly matches the surface features seen by the infrared orbiter Magellan, shown in assigned color. Long wavelength light, such as infrared light, can peer through the clouds of Venus, all the way down to the surface. It’s only because the clouds themselves radiate in the infrared that phosphine can act as an absorber along the line-of-sight.
( Credits: NASA/APL/NRL (left), Magellan Team/JPL/USGS (right))
The atmospheric greenhouse effect on Venus
yields consistently higher temperatures than Mercury.
The surface of Venus, as seen by one of the Soviet Union’s old Venera landers (most likely Venera 14): the only set of spacecraft to ever successfully land and transmit data from that world. The series of Venera landers survived for between 39 minutes to approximately 2 hours; no longer.
( Credit: Veneralanders/USSR)
2.) I’m the most metallic planet.
When it comes to the large, non-gaseous worlds of the Solar System, Mercury has by far the largest metallic core relative to its size. However, it’s Earth that’s the densest of all these worlds, with no other major body comparing in density, owing to the added factor of gravitational compression.
( Credit: Bruce Murray/The Planetary Society)
An early vapor state ensured
Mercury is ~75% metalby mass.
The above image shows an orthographic projection of this global mosaic centered at 0°N, 0°E. The rayed crater Debussy can be seen towards the bottom of the globe and the peak-ring basin Rachmaninoff can be seen towards the eastern edge. Mercury is the Solar System’s innermost planet, and was mapped in detail by NASA’s MESSENGER mission.
( Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)
3.) I’m originally the 8th planet.
The dwarf planet Ceres, shown here, is the largest world in the asteroid belt and the only one known to be in hydrostatic equilibrium. Discovered in 1801 by Giuseppe Piazzi, it was originally classified as a planet: the Solar System’s 8th.
( Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
discovered in 1801is the asteroid belt’s lone dwarf planet.
The four largest asteroids, all shown here, have been imaged with NASA’s Dawn mission and the ESO’s SPHERE instrument. Ceres, the largest asteroid, is the smallest known body in hydrostatic equilibrium. Vesta and Pallas are not, but Hygeia’s status is indeterminate; it may yet be.
( Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA; OSO)
4.) My planetary system contains the most water.
By size, it’s clear that the gas giant worlds vastly outstrip any of the terrestrial planets. In terms of water, however, the giant planets, owing to their lunar systems, can possess more water than even planet Earth does.
( Credit: CactiStaccingCrane/Wikimedia Commons)
That’s Jupiter, whose moons
Ganymede, Callisto, and Europa individually possess more water than Earth.
Although Earth contains the most liquid water on its surface of any of the 8 planets, the most water in any form is found on Jupiter’s moon Ganymede. Next in order is Saturn’s Titan, Jupiter’s Callisto, and Jupiter’s Europa. Planet Earth has only the 5th most water, placing it ahead of Pluto, Dione, Triton, and Enceladus.
5.) I’m the most massive object originating from the Kuiper belt.
Triton’s south polar terrain, as photographed by the Voyager 2 spacecraft and mapped to a spheroid of the appropriate shape and size. About 50 dark plumes mark what are thought to be cryovolcanoes, with those trails being caused by the phenomenon colloquially called ‘black smokers.’
( Credit:NASA; PlanetUser/Wikimedia Commons)
Neptune’s captured moon,
Tritonsurpasses Pluto and Eris in both mass and size.
When you rank all the moons, small planets, and dwarf planets in our Solar System, you find that Triton, the 7th largest moon, has more similarities to Pluto than it does to anything else in the Solar System. Triton is larger and more massive than both Eris and Pluto, and originates from the Kuiper belt as well. At one point, it was the true “king” of the Kuiper belt.
( Credit: Emily Lakdawalla. Data from NASA / JPL, JHUAPL/SwRI, SSI, and UCLA / MPS / DLR / IDA, processed by Gordan Ugarkovic, Ted Stryk, Bjorn Jonsson, Roman Tkachenko, and Emily Lakdawalla)
6.) I’m the lowest density planet.
When we classify the known exoplanets by both mass and radius together, the data indicates that there are only three classes of planets: terrestrial/rocky, with a volatile gas envelope but no self-compression, and with a volatile envelope and with self-compression . Anything above that is a star. Planetary size peaks at a mass between that of Saturn and Jupiter, with heavier and heavier worlds getting smaller until true nuclear fusion ignites and a star is born. Saturn is just about the lowest density planet out there.
( Credit: J. Chen and D. Kipping, ApJ, 2017)
At 0.687 g/cm³, Saturn is
the only planet less dense than water.
Saturn, as photographed here by Cassini during the 2008 equinox, isn’t just round, but is in hydrostatic equilibrium. With its low density and rapid rotation, Saturn is the most flattened planet in the Solar System, with an equatorial diameter that’s more than 10% larger than its polar diameter.
( Credit: NASA/JPL/Space Science Institute)
7.) I possess the strongest winds.
These images of Neptune, from October 7, 2017 with the Hubble Space Telescope, shows the presence of clouds, bands, and varying colors and temperatures across Neptune’s upper atmosphere. The rapid changes reveal Neptune’s wind speeds: the fastest in the Solar System.
( Credit: ESA/Hubble and NASA, Acknowledgment: Judy Schmidt)
With speeds over 1,100 mph (492 m/s),
Neptune’s winds are unsurpassed.
Although, through Galle’s telescope at the Berlin Observatory, Neptune appeared only as a small, faint, blue disk, it did not show up on previous recorded sketches of that very region of sky, as d’Arrest proposed. On September 23, 1846, the 8th planet in our Solar System, Neptune, was discovered.
( Credit: NASA/Voyager 2)
8.) My fragments contaminate Earth.
This scanning electron microscope image of a fragment of the Allen Hills 84001 meteorite contains inclusions that resemble simple life found on Earth. Although this sample is thoroughly inconclusive, bombardment of Earth by extraterrestrial objects is a certainty. If they contain dormant or fossilized life, we could discover it via this method.
3% of all terrestrial meteorites originate there.
Winds at speeds up to 100 km/hr travel across the Martian surface. The craters in this image, caused by impacts in Mars’ past, all show different degrees of erosion. Some still have defined outer rims and clear features within them, while others are much smoother and featureless, evidence of old age and erosion. On Earth, 3% of our meteorites originate from Mars; it is unknown what fraction of Martian impacts originate from Earth-based rocks, and whether life stowed-away on any of them.
( Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO)
9.) I change the most from solstice to equinox.
Infrared images of Uranus (1.6 and 2.2 microns) obtained on Aug. 6, 2014, with adaptive optics on the 10-meter Keck telescope. The white spot is an extremely large storm that was brighter than any feature ever recorded on the planet in the 2.2-micron band. The cloud rotating into view at the lower-right limb grew into a storm that was so large, it was visible even to amateur astronomers at visible wavelengths. These features were not present in 1986, when Voyager 2 flew by Uranus.
( Credit: Imke de Pater, UC Berkeley & Keck Observatory)
It’s Uranus, whose 97° axial tilt
causes planet-wide changes every 21 years.
Although this is a modern, infrared view of our Solar System’s 7th planet, it was only discovered in 1781 through the serendipitous observations of William Herschel. Up until the advent of space telescopes and infrared astronomy, we had no idea that Uranus was ever anything other than featureless.
10.) I’m the final planet to form.
An illustration of what a synestia might look like: a puffed-up ring that surrounds a planet subsequent to a high-energy, large angular momentum impact. This likely represents the aftermath of the collision that resulted in the formation of our Moon. Although our planet has remained intact ever since, an impact with Comet Bernardinelli-Bernstein could create a similar phenomenon.
( Credit: Sarah Stewart/UC Davis/NASA)
It’s us! An impact
50 million years after the other planets formed created today’s Earth-Moon system.
Japan’s Kaguya probe went to and orbited the Moon, which enabled magnificent views of the Earth seen over the lunar surface. Here, the Moon is photographed along its day/night boundary, the terminator, while Earth appears in a half-full phase. From the near side of the Moon, the Earth is always visible; both are the result of the aftermath of an early, giant impact between a Mars-sized protoplanet and a proto-Earth.
( Credit: JAXA/NHK)
Mostly Mute Monday tells an astronomical story in images, visual, and no more than 200 words. Talk less; smile more.