Fireballs
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Fireball 3

Stunning meteor fireball seen over Madrid, Spain

Fireball over Spain
© YouTube/Meteors
This stunning fireball overflew Toledo and Madrid on July 27 at 00:35 local time (22:35 Universal Time on July 26). The event was produced by a rock from an asteroid that hit the atmosphere at around 54.000 km/h.

The fireball began at a height of about 80 km and ended at an altitude of 45 km. It was recorded in the framework of the SMART Project from the astronomical observatories of Calar Alto (Almería, Spain) and La Hita (Toledo, Spain).


Fireball 4

Meteor fireball flies over Andalusia, Spain

Fireball over Spain
© YouTube/Meteors
This ball of fire flew over Andalusia on July 17 at 6:07 local time (4:07 UT). The event was caused by the entry into the Earth's atmosphere of a meteoroid of cometary origin.

The luminous phenomenon began on the province of Jaén, at a height of about 120 km above sea level, and ended at an altitude of about 75 km.


Fireball 2

Slow meteor fireball recorded over Mediterranean Sea

Meteor fireball over Mediterranean sea
© Meteors (CAHA)
This beautiful fireball overflew the Mediterranean Sea on July 26 at 00:18 local time (22:18 Universal Time on July 25). The event was produced by a rock from an asteroid that hit the atmosphere at around 25.000 km/h. The fireball began at a height of about 83 km and ended at an altitude of 36 km. It was recorded in the framework of the SMART Project from the astronomical observatories of Calar Alto (Almería, Spain), La Sagra (Granada, Spain) and Sevilla (Spain).


Cassiopaea

Signs of the times - New comet, Nova in Scutum constellation and Supernova in Pisces!

New Comet ASASSN1 (C/2017 O1)
© Rolando LigustriNew Comet ASASSN1 (C/2017 O1) already glows aqua from carbon-laced gases. The comet is currently visible in the pre-dawn sky through modest-sized telescopes.
It feels like the FedEx guy just pulled up and dropped off a truckload of astronomical goodies. News arrived in my e-mail Monday about a new comet discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN).Founding member Benjamin Shappee and team have 498 bright supernovae and numerous other transient sources to their credit, but this is the group's first comet discovery, ASASSN1 (C/2017 O1).

The 15th-magnitude object was caught before dawn on July 19th in the constellation Cetus using data from the quadruple 14-cm "Cassius" telescope on Cerro Tololo, Chile. Don't be put off by that magnitude. The comet has brightened quickly in the past few days; visual observers are now reporting it at around magnitude +10 with a large (7′), weakly condensed coma. Chris Wyatt of Australia relates that a Swan band filter does a great job enhancing the apparent brightness and contrast of the coma, a sign this is a "gassy" comet.
Comet ASASSN1's location
© StellariumThis wide-view map shows Comet ASASSN1's location at the Cetus–Eridanus border south of Alpha (α) Ceti (Menkar) on July 26th.
Assuming the orbit remains close to the current calculation, Comet ASASSN1 will move northeast across Cetus and Taurus this summer and fall, slowly brightening as it approaches perihelion on October 14th in Perseus. It comes closest to the Earth four nights later, missing the planet by a cool 67 million miles. In a fun twist, ASASSN1 will slow down and spend the entire month of December and much of January within a few degrees of the North Star!

Telescope

Astronomers detect space rock 3 days after it passes close to Earth

Artists rendering of an asteroid passing Earth
© Earth SkyArtist’s concept of an asteroid passing near Earth.
A space rock now designated as asteroid 2017 OO1 was detected on July 23, 2017 from the ATLAS-MLO telescope at Mauna Loa, Hawaii. An analysis of its trajectory revealed it had been closest to Earth on July 20 sometime between 10:27 p.m. to 11:32 p.m. EDT (between 02:27 to 03:32 UTC on July 21).

This means the asteroid's closest approach occurred 2.5 to 3 days before it was seen. Asteroid 2017 OO1 flyby had passed at about one-third the Earth-moon distance, or about 76,448 miles (123,031 km).

Although that's still a safe distance, a fact that stands out is that asteroid 2017 OO1 is about three times as big as the house-sized asteroid that penetrated the skies over Chelyabinsk, Russia in February, 2013, breaking windows in six Russian cities and causing more that 1,000 people to seek treatment for injuries, mostly from flying glass.

Comet

Comets from oort cloud more common threat to Earth than previously thought

Comet
© NASA/JPL-Caltech
"Comets travel much faster than asteroids, and some of them are very big," said Amy Mainzer, co-author based at NASA's Jet Propulsion Laboratory, Pasadena, California, and principal investigator of the NEOWISE mission. "Studies like this will help us define what kind of hazard long-period comets may pose."

"The number of comets speaks to the amount of material left over from the solar system's formation," said James Bauer, lead author of the study and now a research professor at the University of Maryland, College Park. "We now know that there are more relatively large chunks of ancient material coming from the Oort Cloud than we thought."

Comets that take more than 200 years to make one revolution around the Sun are notoriously difficult to study. Because they spend most of their time far from our area of the solar system, many "long-period comets" will never approach the Sun in a person's lifetime. In fact, those that travel inward from the Oort Cloud -- a group of icy bodies beginning roughly 186 billion miles (300 billion kilometers) away from the Sun -- can have periods of thousands or even millions of years.

This illustration shows how scientists used data from NASA's WISE spacecraft to determine the nucleus sizes of comets. They subtracted a model of how dust and gas behave in comets in order to obtain the core size.

Comet 2

New Comet: C/2017 O1

CBET nr. 4414, issued on 2017, July 24, announces the discovery of a comet (magnitude ~15.3) in the course of the "All-Sky Automated Survey for Supernovae" (ASASSN) program, from images taken with the 14-cm "Cassius" survey telescope at Cerro Tololo on July 19.32 UT. The new comet has been designated C/2017 O1.

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 60 seconds each, obtained remotely on 2017, July 23.7 from Q62 (iTelescope network) through 0.50-m f/6.8 astrograph + CCD + f/4.5 focal reducer, shows that this object is a comet with a sharp central condensation surrounded by diffuse coma about 3 arcmins in diameter.

My confirmation image (click on it for a bigger version)
Comet C/2017 O1
© Remanzacco Blogspot
Below you can see the discovery image by ASASSN survey

Fireball 2

Meteor fireball observed over São Paulo, Brazil

 YouTube/Exoss Citizen Science (screen capture)
YouTube/Exoss Citizen Science (screen capture)
On July 17th, just four days after rattling windows and shaking walls scare residents in the region of Campinas, another fireball is registered in the State of São Paulo by Exoss Citizen Science, a Brazilian meteor monitoring organization.


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What it would take to kill all life on Earth

Asteroid impact on earth
© Zloyel/iStock
A giant asteroid crashing into our planet would instantly kill off millions of animals. But the aftermath of such an impact would be even more disastrous: Tsunamis, earthquakes, and vast clouds of dust blocking out the sun would lead to crop failure and mass extinction.

Sixty-five million years ago, just such an event killed off 75% of species on Earth. But to really wipe life off the planet, it would take an astrophysical event so powerful that Earth's oceans would literally boil away, according to a new study. The heat and cosmic radiation would make Earth inhospitable even to tardigrades, among the hardiest organisms ever discovered.

"They've taken a grand question—how resilient is life?—and turned [it] into a well-posed calculation, by focusing on the energy required to boil Earth's oceans," says Joshua Winn, an exoplanets expert at Princeton University, who was not involved in the study. "It's an awful lot of energy."

Fireball 2

Meteor rattles windows and scares residents in Campinas, Brazil

Photo of the Observatory of Campinas shows meteor trajectory in the sky
© EPTVPhoto of the Observatory of Campinas shows meteor trajectory in the sky
Noise and tremor scare residents of Hortolândia and Sumaré on Thursday night

The Municipal Observatory of Campinas (SP) caught the passage of a meteor in the region on Thursday night (July 13th). The cameras captured the moment when a luminous ball appears in the sky. See the meteor's trajectory in the video above. Residents reported feeling the shaking walls and windows and a loud noise.

Astronomer Júlio Lobo explains that "When a meteor falls and explodes, it causes a sonic boom, which usually shakes the walls and windows. [...] When this happens, it produces a meteorite, which is the 'pebble' that will stay on the ground. So if anyone happened to see a falling meteor, communicate us because this is of great scientific importance".

According to the astronomer, the Campinas observatory currently has six cameras, and this is the largest number of cameras in a Brazilian observatory. Many other meteors were recorded on Thursday night.

"We recorded 88 meteors on the same night. There is a network that studies this officially," said the astronomer.


Comment: It is well worth remembering what can come out of the sky, without any warning at all, like the Chelyabinsk meteor fireball.


Even NASA's own space data supports citizens' recent observations, namely the inconvenient fact that meteor fireballs are increasing dramatically.