The most intriguing mystery in astronomy today is the nature of interstellar object 3I/ATLAS. Most astronomers believe it is a comet. However, Avi Loeb of Harvard University famously makes the case that it might be something else--like alien tech.
Into this debate comes new data from the James Webb Space Telescope. A paper just submitted to the Astrophysical Journal Letters reports that 3I/ATLAS looks like a comet, albeit a strange one. Here are the images from JWST:

The infrared space telescope found most of the ingredients we expect to find in comets. There's a fuzzy coma, volatile ices, and all the usual molecules: water (H20), carbon dioxide (CO2), carbon monoxide (CO). If 3I/ATLAS is a spacecraft, it has an uncanny disguise.
However, there's also something strange. The ratios of the different molecules are quite unexpected and don't match what we see in Solar System comets. In particular, the CO2/H20 ratio of 8 ± 1 is extremely high. Only one other comet, C/2016 R2, is known to have similar chemistry, and astronomers have long considered it to be a "freak".

Typical comets have a lot more water in their atmospheres, with H20 almost always outnumbering CO2. It could be that water production in 3I/ATLAS has not yet fully "turned on" because it is still too cold. If so, solar heating might restore ratios to normal. 3I/ATLAS will reach its closest point to the sun (1.36 AU) on Oct. 29, 2025, potentially bringing forth a geyser of water vapor to mix with the other gases.
Or, maybe, 3I/ATLAS is just strange--like it came from another star system. Stay tuned for updates.
https://spaceweather.com/

Earth is passing through a stream of debris from Halley's Comet, source of the annual eta Aquarid meteor shower. In the southern hemisphere, meteor rates are exceeding 20 per hour--an impressive display considering that it is muted by the glare from the nearly full Moon. Observers can look for more eta Aquarids before sunrise on Wednesday, May 6th; after that, the shower will subside. Sky maps: northern hemisphere, southern hemisphere.
www.spaceweather.com

Over the weekend, Comet 46P/Wirtanen made history. The green ball of gas wrapped around a nugget of dirty ice flew past Earth only 11.5 million km away--so close that it cracked the top 10 list of comet flybys during the Space Age. During the hours of closest approach, 46P/Wirtanen appeared in the constellation Taurus alongside the Pleiades star cluster:

Michael Jäger took the picture on Dec. 16th from Turmkogel, Austria. "To create the image, I combined 6-minute exposures through red, green and blue filters," says Jäger.

The colors in Jäger's image are remarkable--a striking contrast of green vs. blue.  Wirtanen's green comes from diatomic carbon (C2)--a gaseous substance common in comet atmospheres that glows green in the near-vacuum of space. The Pleiades, on the other hand, appear blue because the stars themselves are that color. Hot and massive, the Seven Sisters shine their blue light into surrounding clouds of gas and dust, which reflect the azure hue.

46P/Wirtanen is receding from Earth now, but it will still be nearby for days to come. The main challenge for observers is not distance, but rather moonlight. The glare of the waxing Moon will dilute the comet's brightness, making it a challenge to see with the unaided eye. Digital cameras and widefield telescopes will have no trouble, however, capturing the comet's exit. It is currently glowing like a big misty star of 4th magnitude near the horns of the Bull:

NASA is advising the world to pack up and go hiking on the night of August 11-12 to watch a spectacular shooting star show, as the annual Perseid meteor shower is forecast to beat all records this year.

"Forecasters are predicting a Perseid outburst this year with double normal rates on the night of August 11-12," Bill Cooke, from NASA's Meteoroid Environments Office in Huntsville, Alabama, said on Tuesday. Cooke noted that under perfect conditions, we will be treated to up to 200 meteors every hour.

The "outburst" the NASA man is referring to means this year's cosmic dance is set to be far more crowded than usual. The last time the event happened on such a scale was 2009.

The Perseid meteor shower wows spectators with its swift and extremely bright meteors, traveling at a speed of 60km per second. A Perseid meteor is a small piece of debris left in the wake of the ancient Swift-Tuttle comet, which orbits the sun every 133 years. Despite these visits into the inner solar system being so rare, each of them gives off trillions of comet particles. When Earth passes through this trail of debris, the particles enter the planet's atmosphere and break up in bright specs of light.

From down here they seem to fly from the direction of the Perseus constellation, leading to the meteors being given the name "Perseids."

"Here's something to think about: The meteors you'll see this year are from comet flybys that occurred hundreds if not thousands of years ago. And they've traveled billions of miles before their kamikaze run into Earth's atmosphere," Cooke says.

Earth flies through the trail of these comet particles every August, usually grazing the edge of the debris stream. But its trajectory shifts somewhat every now and then thanks to Jupiter's gravity pull, and according to NASA experts this year our planet may be getting a seat in the front row, flying closer to the middle, where there are more particles. In fact, they claim that three or more debris trails will cross paths with Earth in but a few days.

According to NASA, the best opportunity to watch the Perseids will be between midnight and dawn on the morning of August 12. If you're not all that into getting out in the fresh air, the agency has also promised a live broadcast of the shooting star display on its Ustream channel starting at 2am GMT.

The Perseids are no danger to Earth, as even the largest ones mostly burn up in its atmosphere some 80km above the planet's surface. But the outburst could still land spacecraft in a spot of trouble: the bigger particles are capable of causing minor damage to the hulls of rockets and satellites.

Let's hope for the best though, and get the binoculars ready.

© NASA : Halley’s comet.
If you're waiting for Halley's comet to show up exactly 75 years after its 1986 appearance, you may be disappointed. The ball of ice has an orbit that varies by months or even years.

And new research suggests that Venus is responsible for the comet's variations today, rather than the more massive planet Jupiter.

"Comet Halley has been observed throughout history, all the way back to 240 BC by the Chinese," Tjarda Boekholt, an astrophysicist at Leiden Observatory in the Netherlands, told Discover by email.

Erratic Schedule

With many well-documented appearances, scientists quickly realized that the arrival time of the comet was constantly changing. For instance, although it passed Earth in February in 1986, it won't be back until February 2061. In 45 years, it will instead appear in July.

"It is the variation in the time of sightings that provided the first clue to comet Halley's chaotic orbit," Boekholt said. "The orbit of comet Halley is not static, but it is evolving."

Boekholt led a team that investigated the comet's changing orbit. They found that Venus played an important role in revising the comet's orbit in the past, and will probably continue to do so in the future, despite its small stature. Mighty Jupiter often dominates the influence of gravitational bodies due to its high mass, but Venus currently dominates Halley's movements.

Narrowing down how and why Halley's orbit changes can help improve scientists' understanding of how other bodies move in the solar system. "Performing such analysis to other bodies in the solar system, we can obtain a better overview and understanding of chaotic orbits, stable orbits, and the dynamical evolution of the solar system and other planetary systems," says Boekholt.

This is an extract; the whole story, with video, can be found here.

Earth is entering a stream of debris from Halley's Comet, source of the annual eta Aquariid meteor shower. Forecasters expect the shower to peak on the nights around May 5th and 6th with 30+ meteors per hour. The best time to look, no matter where you live, is probably during the dark hours before sunrise on Friday."Although the shower's peak is still days away, the Canadian Meteor Orbit Radar (CMOR) is already detecting strong activity from the eta Aquariid shower," reports physics professor Peter Brown of the University of Western Ontario. The pink "hot spot" in this all-sky radar map from May 3rd shows the location of the shower's radiant (ETA):

"Processing from last night shows more than 200 eta Aquariids with orbits loosely matching that of comet 1P/Halley," Brown says. "The equivalent visible rates are about 40 per hour – almost one per minute! Based on these numbers it is clear that sky watchers are in for a treat over the next few nights."
Got clouds? No problem. You can still experience this meteor shower by listening to it. Meteor radar echoes are being streamed live on Space Weather Radio.
www.spaceweather.com

Discovered in 2013 by the Catalina Sky Survey, Comet Catalina (C/2013 US10) is making a one-time trip through the inner solar system. It swung around the sun last November and is now making its closest approach to Earth: 67 million miles away on Jan. 17th. Dr. Fritz Helmut Hemmerich sends this picture from Tenerife, Canary Islands:

"This is Comet Catalina (C2013US10) during a cloudy morning session on Jan. 16th," says Hemmerich. "I thought the photo could be useful as a finder chart. As the inset shows, the comet is located near the handle of the Big Dipper."

The 6th magnitude comet is too dim for the naked eye, but it is an easy target for backyard telescopes and digital cameras. In fact, Hemmerich's photo was taken using no telescope, just a Sony A7s camera set at ISO3200 for a 45 second exposure.

This is Comet Catalina's first visit to the inner solar system--and its last. The comet's close encounter with the sun in mid-November has placed it on a slingshot trajectory toward interstellar space. Enjoy it now. Once it recedes from Earth, we may never see it again. Browse the realtime comet gallery for more sightings.     www.spaceweather.com

Earth is entering a stream of gravelly debris from "rock comet" 3200 Phaethon, source of the annual Geminid meteor shower. Forecasters expect peak rates to occur on Dec. 13-14, when dark-sky observers in both hemispheres could see as many as 120 meteors per hour. Observing conditions will be nearly ideal because the shower peaks just a few days after the New Moon. Stay tuned for updates and, meanwhile, listen for Geminid echoes in the audio feed from our live meteor radar.

A stunning fireworks show will be thrown by Mother Nature overnight on Tuesday 17 November, as the Leonid meteor shower sends out a series of spectacular fireballs and shooting stars. The annual lights show contains some of the fastest meteors in existence. "Leonids travel at speeds of 71 km (44 miles) per second, and are considered to be some of the fastest meteors out there," NASA said in a statement.

Skywatchers hoping to see the light show with their own eyes are in luck, according to NASA, which says that a "waxing-crescent moon will set before midnight, leaving dark skies to view these bright and colorful meteors."  Those who want a front-row seat should head outdoors at around midnight, local time, says NASA.  "Find an area well away from city or street lights...orient yourself with your feet towards east, lie flat on your back, and look up, taking in as much of the sky as possible," the space agency wrote online, noting that the show will last until dawn.

But although the Leonid shower has produced tens of thousands of meteors per hour in the past, this year's event won't be quite as remarkable. Viewers should at most expect 10 to 20 meteors per hour, according to Space.com.

The Leonids are created when Earth travels through a trail of debris shed by Comet Tempel-Tuttle. However, since the comet is now just about as far from the sun as it gets during its roughly 33-year orbit, there's not a lot of debris for Earth to collide with - which results in a less impressive meteor shower than previous years.

Those with compromised views due to clouds or light pollution can watch the meteor shower online, via a Leonids webcast hosted by the Slooh Community Observatory, which will take place at 01:00 GMT on Wednesday. The webcast will feature live shots from five different countries on four continents.

Asteroid 2015 TB145 isn't the only cosmic visitor paying our planet a trick-or-treat visit over the coming week. With any luck, the Northern Taurid meteor shower may put on a fine once a decade show heading into early November.  About once a decade, the Northern Taurid meteor stream puts on a good showing. Along with its related shower the Southern Taurids, both are active though late October into early November.

Specifics for 2015

This year sees the Moon reaching Full on Tuesday October 27th, just a few days before Halloween. The Taurid fireballs, however, have a few things going for them that most other showers don't. First is implied in the name: the Northern Taurids, though typically exhibiting a low zenithal hourly rate of around 5 to 10, are, well, fireballs, and thus the light-polluting Moon won't pose much of a problem. Secondly, the Taurid meteor stream is approaching the Earth almost directly from behind, meaning that unlike a majority of meteor showers, the Taurids are just as strong in the early evening as the post midnight early morning hours. As a matter of fact, we saw a brilliant Taurid just last night from light-polluted West Palm Beach in Florida, just opposite to the Full Moon and a partially cloudy sky.

In stark contrast to the swift-moving Orionids from earlier this month, expect the Taurid fireballs to trace a brilliant and leisurely slow path across the night sky, moving at a stately 28 kilometre per second (we say stately, as the October Orionids smash into our atmosphere at over twice that speed!).

© NASA
A 2013 Taurid fireball captured by an All-Sky cam, plus a near-Full Moon.

Ever since the 2005 event, the Northern Taurids seemed to have earned the name as "The Halloween Fireballs" in the meme factory that is the internet. It's certainly fitting that Halloween should have its very own pseudo-apocalyptic shower. The last good return for the Northern Taurids was 2005-2008, and 2015 may see an upswing in activity as well.

Obviously, something interesting has to be occurring on Comet 2P Encke—the source of the two Taurid meteor streams—to shed the pea-sized versus dust-sized material seen in the Southern and Northern Taurids. With the shortest orbital period 3.3 years of all periodic comets known, the Taurid meteor stream—like Encke itself—follows a shallow path nearly parallel to the ecliptic plane.

Discovered in 1822 by astronomer Johann Encke, Comet 2P Encke has been observed through many perihelion passages over the last few centuries, and passes close to Earth once 33 years, as it last did in 2013.

Read more here.

On 29 July, Rosetta observed the most dramatic outburst yet, registered by several of its instruments from their vantage point 186 km from the comet. They imaged the outburst erupting from the nucleus, witnessed a change in the structure and composition of the gaseous coma environment surrounding Rosetta, and detected increased levels of dust impacts.  Perhaps most surprisingly, Rosetta found that the outburst had pushed away the solar wind magnetic field from around the nucleus.

The rest of this article can be read here.

Earth is entering a stream of debris from Comet Swift-Tuttle, source of the annual Perseid meteor shower. Forecasters expect meteor rates to peak at 100+ per hour on the night of Aug. 12-13 when our planet passes through the heart of the debris stream. Perseids produce more fireballs than any other meteor shower of the year, so stay tuned for a good show. [meteor radar]   www.spaceweather.com