[SYFY WIRE − BAD ASTRONOMY − 21.01.2020 − syfy.com]

Hey,

maybe the dinosaur-killer asteroid

really *did* act alone!

Someone's about to have a VERY bad day

We're still not really sure what killed the dinosaurs.

I mean that both in general and specifically. Yes, there was an asteroid impact. We know that 66 million years ago, an object roughly 10 kilometers across, either an asteroid or a comet, slammed into what is now the Gulf of Mexico just off the coast of Yucatan. The crater is something like 150 kilometers across and 20 deep, and the impact was so catastrophic that 75% of all species died out, including the non-avian dinosaurs. This is called the Cretaceous-Paleogenic, or K-Pg, extinction.

(texto/legenda e imagem: syfy.com e shutterstock/Esteban de Armas)

Meteor in Chelyabinsk impact was twice as heavy as initially thought

(NATURE – 06.11.2013)

A three-dimensional simulation of the 15 February airburst over Chelyabinsk/Russia

The asteroid that exploded on 15 February this year near the city of Chelyabinsk in the Urals region of Russia was the largest to crash to Earth since 1908, when an object hit Tunguska in Siberia. Using video recordings of the event, scientists have now reconstructed the asteroid's properties and its trajectory through Earth’s atmosphere. The risk of similar objects hitting our planet may be ten times larger than previously thought, they now warn.

The fireball’s early-morning flight through the sky over the Urals was observed by many people and captured by numerous video cameras. To observers on the ground, it shone 30 times brighter than the Sun, and had an energy equivalent to more than 500 kilotons of TNT. An analysis of calibrated observations now provides a precise picture of the asteroid’s last ride and reveals surprising details of its likely cosmic origin.

The rock was an ordinary chondrite from the asteroid belt located between the orbits of Mars and Jupiter, as revealed by its trajectory and by its elemental and mineral composition, mainly silicates that formed the Solar System billions of years ago. At the time it entered the atmosphere, its mass was of the order of 12,000–13,000 metric tonnes, report two studies published online today in Nature and another study published at the same time in Science. This is nearly twice as heavy as initial estimates had suggested and also larger than revised estimates published in June.

The asteroid roared through Earth’s upper atmosphere at an initial speed of around 19 kilometres per second — more than 50 times the speed of sound. At an altitude of between 45 and 30 kilometres, the heavily fractured, and hence rather fragile, body broke into pieces and finally burst into gas and dust at around 27 kilometres' altitude.

“Luckily, most of the kinetic energy was absorbed by the atmosphere,” says Jiří Borovička, an asteroid researcher at the Astronomical Institute, part of the Academy of Sciences of the Czech Republic in Ondřejov, near Prague. ”A more solid rock that might have blasted closer to the ground would have caused considerably more damage.”

(artigo/parcial – nature.com)

When I was under the velvet black skies of western Texas a few months ago I had a magnificent view of the star-studded bulge of our galaxy, in the direction of the summer constellation Sagittarius.

How many advanced civilizations might be in this hub of the Milky Way? I pondered. After all, this is the direction where the mysterious "WOW" radio signal that was detected three decades ago came from.

The problem is that we are embedded in a thick forest of stars, and identifying the location of an extraterrestrial civilization -- one that's attempting to contact us -- is the proverbial needle-in-haystack search as the SETI scientists always say.

Therefore, it would make sense to go looking at a neighboring "forest," or rather nearby galaxy, for evidence of extraterrestrial intelligence.

NASA's Hubble Space Telescope is conducting a multi-year survey across a swath of the neighboring Andromeda galaxy (M31). The images are filled with so many resolved stars that they resemble at grains of sand on a beach. This could make an excellent citizen science project, to scour the Andromeda fields for anomalous-looking regions.

Could Terrorist Aliens Cyber attack us?

Super-Civilizations Might Live Off Black Holes.

Asteroid forensics may point to Alien space miners.

(discovery.com)