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Cosmic Space

What to know before you go comet-hunting

This summer’s sky spectacle is a shooting star that was discovered in March by NASA’s Near-Earth Object Wide-Field Explorer, or NEOWISE. Comet NEOWISE (also known as C/2020 F3) zoomed around the sun last week, and is now visible to the naked eye. But only if you know exactly where, when and how to look.

Although there’s lots of buzz about NEOWISE, this is no “great comet” — just a pretty good one. If you’re expecting to look up above your head and see a celestial portent of “Game of Thrones” proportions, you’re going to be disappointed.

But if you’re angling to see this season’s most-talked-about sky show with your own eyes, here are five strategies to maximize your chances:

Go late or go early: Because it’s so soon after the northern solstice, the celestial alignments make it theoretically possible to see Comet NEOWISE in morning or evening skies, with emphasis on the word “theoretically.”

For the next few days, the comet will be higher in the sky in the morning, which means predawn viewing is preferred. The best time is around 3 to 4 a.m.; the farther north you are, the earlier you should get up. Around July 15, the comet’s outward trajectory from the sun will turn it into more of an evening star, with prime time coming at 10:30 p.m., about an hour and a half after sunset.

Look north: Your viewing spot should have an unobstructed view to the northern horizon — to the northeast for morning viewing, or to the northwest for the evening. To find optimal views of the horizon, scan Google Maps (with Street View). And to figure out exactly where to look in the sky, study the charts from Sky & Telescope, SpaceWeather.com, The Sky Live, Heavens Above and EarthSky.

Comet NEOWISE should be visible in the northeast by 3 a.m. July 11 — close to the horizon and to the left of Venus, the brightest object in eastern skies.

Seek clarity: The fact that NEOWISE is so close to the horizon means that sky conditions are crucial. There’s a good chance the comet could be lost in hazy or humid skies. And if there are clouds stretching across the horizon, that could be a deal-breaker. Finding out you’re clouded out at 3 a.m. is a truly rude awakening.

To determine if the forecast is favorable, click on over to Digital.Weather.gov, focus in on your viewing area and select “Sky Cover (%)” from the drop-down menu. Then move the slider bar to your planned viewing time (for example, “At Jul 11, 3 a.m.”) and check whether conditions are expected to be blue (set your alarm) or gray (sleep in).

Bring binoculars: Although NEOWISE is bright enough for naked-eye viewing, your naked eyes will see it pretty much as a fuzzy star. To make out the comet’s tail clearly, you’ll probably need to break out the binoculars or a telescope.

Skywatchers have been putting up some impressive pictures of NEOWISE and its double tail — a curving tail of cosmic dust illuminated by the sun, plus a dimmer, bluish tail of ions streaming straight out. You just have to remember that those photos are typically enhanced or stacked to bring out details you won’t be able to see with your own eyes.

Be realistic: Most celestial phenomena are subtler than the hype makes them out to be, so don’t get frustrated if that turns out to be the case for NEOWISE. While you’re out there comet-hunting, take a moment to check out other celestial wonders — ranging from the International Space Station and passing satellites to the moon, planets and meteors.

Even if you miss seeing NEOWISE with your naked eyes, you can still connect with the comet by checking out the views from the space station, NASA’s Parker Solar Probe and the scores of dedicated comet-hunters whose photos appear on SpaceWeather.com, EarthSky and other online galleries.

Update for 2 p.m. PT July 13: I discovered that 4 a.m. is really too late to look for the comet in northern-latitude locations (like Seattle). I totally missed seeing it at 4 a.m. on July 11 — but had much better luck at 3 a.m. on July 13, when it was still dark enough to spot NEOWISE in advance of the predawn glow. I’ve changed the time references in this story for the benefit of those still trying to catch sight of the comet before dawn.

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Hubble spots interstellar comet as it rounds sun

Comet 2I/Borisov
Comet 2I/Borisov appears as a bright dot within a haze of dust, with a distant spiral galaxy in the background of the Hubble Space Telescope image, taken on Nov. 16. The comet was about 203 million miles from Earth when the picture was taken. (NASA / ESA / UCLA / D. Jewitt)

The Hubble Space Telescope has snapped the best images to date showing the interstellar comet known as 2I/Borisov, and one of the pictures shows a faraway spiral galaxy just off to the side.

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Second interstellar visitor confirmed

2I/Borisov
A two-color composite image from the Gemini North Multi-Object Spectrograph in Hawaii shows the interstellar object 2I/Borisov. Blue and red dashes are images of background stars that appear to streak due to the comet’s motion. (Gemini Observatory / NSF / AURA Image / Travis Rector)

Two years after astronomers made their first detection of a celestial object that came into our solar system from the neighborhood of another star, they have now confirmed the existence of another one.

The comet, originally known as C/2019 Q4 (Borisov), was discovered on Aug. 30 by Gennady Borisov at the MARGO observatory in Crimea, a region that’s contested by Ukraine and Russia.

Based on an analysis of night-by-night observations, the International Astronomical Union announced today that the comet is “unambiguously interstellar in origin,” coming in from far beyond our solar system. The IAU also gave the object a new name to befit its interstellar status: 2I/Borisov.

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Hubble hints that interstellar object is a comet

Observations made by the Hubble Space Telescope and ground-based observatories indicate that the cigar-shaped interstellar object known as ‘Oumuamua got an unexpected boost in speed and a shift in its trajectory as it passed through the inner solar system last year. Scientists surmise that the source of the boost was an outflow of gas and dust from ‘Oumuamua, which suggests that the object is more like an active comet than a passive asteroid.

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Scientists say Pluto was made from a billion comets

Pluto composition
These maps, assembled using data from the Ralph spectral imager on NASA’s New Horizons probe, shows the relative concentration of four chemicals on Pluto’s surface. Methane is shown in purple, nitrogen in yellow, carbon monoxide in green, and water ice in blue. (NASA / JHUAPL / SwRI Images)

Did Pluto form like its closer-in brethren in the solar system, or is it the result of an agglomeration of comets from the edge of the solar system? A study published in the journal Icarus makes the case for comets.

To reach that conclusion, Christopher Glein and J. Hunter Waite Jr. of the Southwest Research Institute compared chemical analyses from NASA’s New Horizons mission to Pluto with readings from the European Space Agency’s Rosetta mission to Comet 67P/Churyumov-Gerasimenko.

The result is what’s known as the “giant comet” cosmochemical model of Pluto formation.

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Animated GIF shows ‘snow’ on Rosetta’s comet

It’s been 19 months since the European Space Agency’s Rosetta mission to Comet 67P/Churyumov-Gerasimenko ended, but the probe’s pictures stirred up a fresh flurry of excitement this week.

Or are those snow flurries?

The excitement is over 33 pictures that were snapped back on June 1, 2016, and posted to Rosetta’s online archive last month. The sequence, captured from a distance of several miles over the course of about 25 minutes, shows the comet’s Cliffs of Hathor with boulders strewn about.

One by one, the pictures are interesting enough. But when a Twitter user with the handle Landru79 (a.k.a. Jacint Roger Perez) put them together in a one-second animated GIF, the scene really came to life.

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Go to a comet? Or Titan? NASA sets up showdown

Dragonfly probe
An artist’s conception shows the sequence leading to the landing of the Dragonfly probe and the deployment of its rotorcraft on Titan. (NASA Illustration)

A rotorcraft that could flit around the Saturnian moon Titan and a probe that could bring a sample back from an already-famous comet have emerged as top prospects for a future NASA mission.

Those two mission concepts were selected for further study from a list of 12 proposals that were submitted for NASA’s New Frontiers portfolio, aimed at space missions with a development cost cap of about $850 million.

Examples of existing New Frontiers projects include the Juno orbiter circling Jupiter, the OSIRIS-REx spacecraft that’s on its way to sample a near-Earth asteroid, and the New Horizons probe that flew past Pluto and is now heading toward another icy object on the edge of the solar system.

A showdown is expected to result in one of the two new mission concepts moving onward to its development phase in 2019, NASA said today.

Both concepts call for robotic probes to be launched in the 2020s and yield results in the 2030s.

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How to spot a lunar eclipse and that comet

A penumbral lunar eclipse not quite as deep as the one we’re about to see occurred over the Far East in November 2012. (Hong Kong Space Museum Photo via Sky & Telescope)
A penumbral lunar eclipse not quite as deep as the one we’re about to see occurred over the Far East in November 2012. (Hong Kong Space Museum Photo via Sky & Telescope)

Tonight’s the night when a lunar eclipse dims the full moon, and when a recently discovered green comet comes closest to our planet. But unless you know what’s coming, you’re almost certain to miss them.

You may miss them anyway, depending on the sky conditions. The forecast for the Seattle area calls for partly cloudy skies with a 20 percent chance of rain.

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Mission to a comet ends with bittersweet bang

Rosetta cartoon
The Rosetta probe inspired a series of kid-friendly cartoons. (Credit: ESA)

The European Space Agency’s Rosetta probe today descended to a mission-ending impact on the comet that it followed for more than two years.

The car-sized probe continued to transmit data as it dove toward the surface of Comet 67P/Churyumov-Gerasimenko, 446 million miles from Earth. When the data stream flatlined, scientists and engineers at ESA’s mission control in Darmstadt, Germany, knew it was all over.

The end was greeted at 1:19 p.m. CEST (4:19 a.m. PT) with a prolonged “Ohhh,” followed by applause and hugs.

“This is it,” said Rosetta mission manager Patrick Martin. “I can announce the full success of this historic descent of Rosetta toward 67P, and I declare hereby the mission operations ended for Rosetta. … Farewell, Rosetta. You’ve done the job.”

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Long-lost lander located in a comet’s crack

Image: Philae lander
A close-up shows the 3-foot-wide Philae lander from a distance of 1.7 miles. (Credit: ESA / Rosetta / MPS for OSIRIS Team / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA)

After almost two years’ of searching, the European Space Agency’s Rosetta spacecraft has shown scientists what happened to the Philae lander when itbounced onto the surface of a comet – and why it went out of contact.

The answer to the mystery comes less than a month before the $1.4 billion Rosetta mission’s end.

Rosetta’s OSIRIS camera spotted the boxy, 3-foot-wide Philae lander stuck in a dark crack on Comet 67/Churyumov-Gerasimenko, more than 420 million miles from Earth.

The comet has been the object of Rosetta’s study since August 2014. Philae was pushed out from the main spacecraft and descended to the surface that November. The lander was supposed to beam up a stream of data about the comet’s composition. It did provide three days’ worth of data, but then the solar-powered probe fell silent.

Rosetta’s scientists determined that the lander had bounced on the surface, and spent months analyzing radio data and imagery from the main spacecraft in an attempt to figure out where it ended up. They assumed that Philae had fallen someplace dark where it couldn’t recharge its batteries.

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