Winter Solstice, Ursid Meteor Shower, and Cold Moon are Happening Tonight

iStock.com/Nadasa
iStock.com/Nadasa

Sky-gazers have one more big night to get excited about before 2018 comes to a close. On Friday, December 21, a cold moon and the Ursid meteor shower fall on the longest night of the year, presenting a rare, end-of-the-year treat for astronomy fanatics.

The Ursids appear in the night sky every year around December 17 through the 26. The shower is on the tamer side, peaking at five to 10 meteors per hour in a typical year, but it's been known to spike unexpectedly with as many as 100 meteors flaring in an single hour.

This year, the peak night of the shower coincides with two big celestial events. Friday, December 21 marks the winter solstice—the time when the Northern Hemisphere is tilted farthest from the Sun, giving us the shortest day and the longest night of the year. It's also the night of a cold moon. A cold moon is a regular full moon that appears during December. Like a strawberry moon, the first full moon of summer; and a harvest moon, the first full moon of autumn, the name refers to a certain time of year rather than anything special going on with the celestial body.

A cold moon hasn't fallen within 24 hours of winter solstice since 2010, and it won't happen again until 2029. Though it makes for an exciting trifecta, the full cold moon will unfortunately make the Ursids harder to spot the night of December 21 and the morning of the 22nd. If you don't catch them at their peak tonight and tomorrow, the shower is expected to continue into next week.

11 Photos From the Opportunity Rover's Mission on Mars

NASA
NASA

In 2004, the rover Opportunity landed on Mars. Originally intended to serve a mere 90-day mission, the rover instead beamed back scientific discoveries for 15 years. But since a massive dust storm in 2018, the rover Opportunity ceased sending data—and now, NASA has declared its groundbreaking mission complete. (Its twin rover, Spirit, ended its mission in 2011.) Opportunity is the longest-serving robot ever sent to another planet. Let's celebrate Opportunity's Mars mission with a look at the images it captured.

1. Opportunity rover gets its first 360° shot.

Rover Opportunity's 360° photo of Mars
NASA/JPL/Cornell 

This 360° panorama, comprised of 225 frames, shows Mars as it was seen by the Opportunity rover on February 2, 2004. You can see marks made by the rover's airbags, made as Opportunity rolled to a stop. Here's a larger version of the photo.

2. Opportunity rover finds a meteorite.

Opportunity rover's photo of a meteorite on Mars
NASA/JPL/Cornell

This meteorite, found by Opportunity on January 19, 2005, was the first meteorite ever identified on another planet. The rover's spectrometers revealed that the basketball-sized meteorite was composed mostly of iron and nickel.

3. Opportunity rover shoots the Erebus Crater and drifts.

Opportunity rover's photo of Erebus craters and drift
NASA/JPL-Caltech/Cornell

On October 5, 2005—four months after Opportunity got stuck in an area NASA nicknamed "Purgatory Dune"—the rover skirted wind-deposited drifts in the center of the Erebus Crater, heading west along the outcrop (the light-toned rock) on the crater's rim, and snapped this photo with its PanCam.

4. Opportunity rover captures Martian rock layers.

Opportunity rover's photo of layers on Mars
NASA/JPL/Cornell

Located on the western ledge of the Erebus Crater, this ledge—called "Payson"—has a diverse range of primary and secondary sedimentary layers formed billions of years ago. According to NASA, "these structures likely result from an interplay between windblown and water-involved processes." Opportunity snapped this photo on April 5, 2006.

5. Opportunity rover comes to Cape Verde.

Opportunity rover's photo of Cape Verde
NASA/JPL-Caltech/Cornell

On October 20, 2007, Opportunity celebrated its second Martian birthday (one Martian year = 687 Earth days) by snapping this photo of Cape Verde, a promontory that juts out of the wall of the Victoria Crater. Scattered light from dust on the front sapphire window of the rover's camera created the soft quality of the image and the haze in the right corner.

6. and 7. Opportunity rover is hard at work on Marquette Island.

Opportunity rover's photo of Marquette Island
NASA/JPL-Caltech

This photo shows Opportunity approaching a rock called "Marquette Island" on November 5, 2009. Because its dark color made it stick out, the rover team referred to the rock—which investigations suggested was a stony meterorite—as "Sore Thumb." But it was eventually renamed, according to NASA, using "an informal naming convention of choosing island names for the isolated rocks that the rover is finding as it crosses a relatively barren plain on its long trek from Victoria Crater toward Endeavour Crater."

On November 19, 2009, the rover used its rock abrasion tool to analyze a 2-inch diameter area of Marquette, which scientists called "Peck Bay."

8. Opportunity rover encounters SkyLab Crater.

Opportunity rover's photo of SkyLab Crater
NASA/JPL-Caltech

Opportunity snapped a photo of this small crater, informally called Skylab, on May 12, 2011. Scientists estimate that the 30-foot crater was formed within the past 100,000 years. Click the photo for a larger version. You can also see the crater in stereo if you have a pair of anaglyph glasses!

9. Opportunity rover sees its shadow.

Opportunity rover's selfie
NASA/JPL-Caltech

On its 3051st day on Mars (August 23, 2012), Opportunity snapped this photo of its own shadow stretching into the Endeavour Crater.

10. Opportunity rover sees its first dust devil.

Opportunity rover's photo of a dust devil
NASA/JPL-Caltech/Cornell University/Texas A&M

Though its twin rover, Spirit, had seen many dust devils by this point, Opportunity caught sight of one for the first time on July 15, 2010.

11. Opportunity rover snaps a selfie.

Opportunity rover's self-portrait
NASA/JPL-Caltech/Cornell University/Arizona State University

A girl sure can get dusty traversing the Martian plains! Opportunity snapped the images that comprise this self-portrait with its panoramic camera between January 3 and January 6, 2014, a few days after winds blew off some of the dust on its solar panels. The shadow belongs to the mast—which is not in the photo—that the PanCam is mounted on.

Do Mission Control Personnel Go Through as Many Simulations as Astronauts?

David McNew, Getty Images
David McNew, Getty Images

Jared Olson:

Mission control personnel go through a lot more simulations than astronauts, as the flight controller needs to develop very specialized skills and knowledge. On the other hand, astronauts in general need to develop the appropriate depth of knowledge across many disciplines. So shorter classes targeted to their needs are used instead to make the best use of their limited time.

I was the robotics instructor for the EVA simulation (or sim) yesterday and the rig (the simulator system) was not behaving for me. Things were up and running quickly, but after I simulated the main robotics computer having a fatal software fault things went downhill. The team rebooted it to recover, as expected, but the rig did not cleanly handle the reboot.

Suddenly it would not accept any commands to the robot arm. The hand controllers were not communicating. And the astronauts' laptop would not connect.

Eventually, I ran out of troubleshooting options and had to tell my three robotics flight controllers in training that all this was unplanned and the sim was not going to go as expected for them. Other disciplines had "scripting priority," as there were controllers who were assigned to use this sim as an evaluation toward their certifications. I did not have the leverage to disrupt the sim by halting the rig to reset the robotics simulator.

Flight controllers go through so many sims partly because of days like this—where, for whatever reason, they don't get as much "content" as we'd like. I told my guys to greencard that the arm simulator was working as expected, which means that they had to pretend they were seeing all the telemetry indications that would normally happen for the arm supporting an EVA. Basically: Just follow along and pretend.

Each simulation is unique in terms of the coordination required with other disciplines, the malfunctions they get to work through, and the timing involved in planning. Throughout their training flow they need to display their ability to work through a broad enough variety of cases before we can call them "certified." How much they get out of each sim can be a roll of the dice.

This post originally appeared on Quora. Click here to view.

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