MORNING CONJUNCTION OF PLANETS: Set your alarm for dawn. Venus and Mars are converging for a close encounter, appearing low in the eastern sky just before the rising sun. At closest approach on Thursday morning, Oct 5th, the bright Goddess of Love and the dimmer God of War will lie no more than 0.25 degrees apart. Take a look! It's a nice way to begin the day. Sky maps: Oct. 4th, 5th, 6th.
MAJOR SPACE WEATHER EVENT ON MARS: More than 150 years after it happened, scientists are still taking about the Carrington Event—a solar storm in Sept. 1859 that sparked Northern Lights as far south as Cuba and sprayed the entire surface of Earth with high energy radiation.
On our planet, such global events are rare. On Mars, they happen surprisingly often—in fact, there was one just a few weeks ago.
The storm began on Sept. 10, 2017--a day the sun was supposed to be quiet: The solar cycle is currently at low ebb, near Solar Minimum, and strong flares are rare. Nevertheless, sunspot AR2673 erupted, producing a powerful X8-class solar flare that accelerated a potent spray of charged particles into space.
In a matter of hours, a "ground level event" (GLE) was underway on Mars. GLEs occur when energetic particles normally held at bay by a planet's atmosphere or magnetic field penetrate all the way to the ground. Mars rover Curiosity detected the radiation spike as it crawled just south of the Martian equator.
"Radiation levels suddenly doubled and they remained high for nearly two days," says Don Hassler of the Southwest Research Institute, principal investigator for Curiosity's Radiation Assessment Detector (RAD). "This is the largest event we have seen since Curiosity landed in 2012."
Earth was in the line of fire, too, but our planet's magnetic field and thick atmosphere mitigated the effect of the storm. The terrestrial GLE on Sept. 10th was restricted to polar regions and amounted to a meager 6% increase–a tiny fraction of what happened on Mars.
Mars got walloped because, simply put, it is more vulnerable to space weather. The Red Planet has no global magnetic field to protect it, and an atmosphere only 1% as thick as Earth's. Energetic particles from the Sept. 10th explosion peppered the entire dayside surface of Mars while auroras fringed the upper atmosphere all around the globe.
NASA's MAVEN spacecraft saw the auroras using its ultraviolet imager. "If a human had been present, with eyes sensitive to visible light, they would have probably seen Mars lit up in green light (557.7nm) much like auroras on Earth," says Sonal Jain of the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado.
Click to play a movie of the UV auroras on Mars
"Sonal had the excitement of being blown away when the raw data come in," says his colleague Nick Schneider, also of LASP. "The auroras were 25 times brighter than the previous record." Both scientists work with MAVEN data and specialize in Martian auroras.
"These global events are really interesting," says Schneider. "On Earth It takes a truly extreme solar storm to cause global havoc thanks to the strength of our magnetic field. Mars' lack of a global magnetic field means that planet-wide events are far more common. Indeed, since MAVEN went into Mars-orbit 3 years ago, we've seen a bunch of auroral displays that were probably global, even though this has been a really wimpy solar cycle."
Hassler agrees. "Curiosity has seen 5 ground level events since 2012. They are not uncommon," he says, "and they will probably grow stronger in the years ahead as we move through Solar Minimum and return to a more active phase of the solar cycle."
Planners of future human missions to Mars will have to take into account the frequency of these "Martian Carrington Events," increasingly revealed by rovers and orbiters of the Red Planet. Meanwhile, researchers are still poring over data from the latest, hoping to learn more. "Analysis of these observations, both at Mars and Earth, is just beginning," says Hassler, "so stay tuned." Free: Aurora Alerts
Realtime Space Weather Photo Gallery
SOLAR ECLIPSE IN THE STRATOSPHERE: On Aug. 21st during the Great American Solar Eclipse, the students of Earth to Sky Calculus launched 11 space weather balloons from the path of totality. They aimed to photograph the Moon's shadow from the stratosphere--and they succeeded. Looking down from a point more than 100,000 feet above Earth's surface, this GoPro video shows the inky-black shadow of the Moon darkening a 70-mile-wide patch of Wyoming and Nebraska:
This video was assembled and edited by filmmaker Ginger Perez, a founding student member of Earth to Sky Calculus. The payload was sponsored by the Southern Maine Community College with Maine students joining the launch team as space weather balloon "trainees."
Our next solar eclipse mission is already set: We plan to launch space weather balloons from Chile into a total eclipse on July 2, 2019. That one will be a sunset eclipse with the sun low on the horizon during the flight. The teams are looking forward to photographing the Moon's stretched-out shadow fringed by lovely sunset colors. Stay tuned for that!
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