Astronomy

My suspicion is that life doesn't need a lot of time, perhaps a few billion years. What is nice is that it should have a safe place to be for much longer. Of course the habitable zone changes over time. I suspect that is the same with dwarf stars.

Perhaps the next question I would have is how long can a planet with a red dwarf star expect to remain in its habitable zone?

The answer is in the second paragraph in my post:

Red dwarf planets are potentially key places to search for life, not just because there are so many of them, but also because of their incredible longevity. Unlike the sun, which will die in a few billion years, red dwarfs will take trillions of years to burn through their fuel, significantly longer than the age of the universe, which is about 13.8 billion years old. This longevity may give life ample time to develop on the planets that orbit these stars..

In short, longer than the universe has been in existence.

Water, water everywhere: even on a pure metal asteroid...

On Psyche, the largest asteroid in the solar system.

http://www.universetoday.com/131738/...ater-deposits/

The James Webb Space Telescope is ready for launching: http://www.space.com/34593-james-web...18-launch.html. It is the new, much larger and more efficient space telescope since the Hubble Space Telescope. We should learn a lot from it once it is launched and ready to start work.

The telescope will be much more powerful than even Hubble for two main reasons, Mather said at the conference. First, it will be the biggest telescope mirror to fly in space. "You can see this beautiful, gold telescope is seven times the collecting area of the Hubble telescope," Mather said. And second, it is designed to collect infrared light, which Hubble is not very sensitive to.

Earth's atmosphere glows in the infrared, so such measurements can't be made from the ground. Hubble emits its own heat, which would obscure infrared readings. JWST will run close to absolute zero in temperature and rest at a point in space called the Lagrange Point 2, which is directly behind Earth from the sun's perspective. That way, Earth can shield the telescope from the sun's infrared emission, and the sun shield can protect the telescope from both bodies' heat.

The telescope's infrared view will pierce through obscuring cosmic dust to reveal the universe's first galaxies and spy on newly forming planetary systems. It also will be sensitive enough to analyze the atmospheres of exoplanets that pass in front of their stars, perhaps to search for signs of life, Mather said.

NASA has now got an asteroid warning system, with 5 days notice of any major threat to Earth. Sounds good. See: http://www.universetoday.com/131737/...-days-warning/:

Everyone knows it was a large asteroid striking Earth that led to the demise of the dinosaurs. But how many near misses were there? Modern humans have been around for about 225,000 years, so we must have come close to death by asteroid more than once in our time. We would have had no clue.

Of course, it’s the actual strikes that are cause for concern, not near misses. Efforts to predict asteroid strikes, and to catalogue asteroids that come close to Earth, have reached new levels. NASA’s newest tool in the fight against asteroids is called Scout. Scout is designed to detect asteroids approaching Earth, and it just passed an important test. Scout was able to give us 5 days notice of an approaching asteroid.

I found this article interesting and the Max Planck Institute is a top research center in Germany.

"Searching for aliens who already know we're here
Astronomers suggest that future searches focus on that part of the sky in which distant observers can notice the yearly transit of Earth in front of the Sun"
http://www.astronomy.com/news/2016/0...know-were-here

That link you sent me, Danik, was interesting. This quote I found particularly intriguing:

Not every star is equally well suited as a home of extraterrestrial life. The more massive a star, the shorter is its life span. Yet, a long stellar life is considered a prerequisite for the development of higher life forms. Therefore the researchers compiled a list of stars that are not only in the advantageous part of the sky, but also offer good chances of hosting evolved forms of life, that is, intelligent life. The researchers compiled a list of 82 nearby Sun-like stars that satisfy their criteria. This catalog can now serve as an immediate target list for SETI initiatives.

But astronomers are far from knowing every star in our Milky Way. The more distant a star, the dimmer its light appears. And the small, particularly long-lived stars are also particularly faint. In order to estimate how many stars in addition to the 82 nearby ones could reside in Earth’s transit zone, Heller and his Canadian colleague Ralph Pudritz projected the celestial sphere onto a model of the stellar density of our galaxy. The result: About 100,000 nearby stars could harbor planets with inhabitants who could have discovered us and who could be trying to contact us.

A part of these planets might be discovered with the PLATO mission of the European Space Agency, scheduled for 2024. René Heller from MPS is also involved in this mission. PLATO will use the transit method to find small planets, some of them possibly Earth-like, around bright stars.

It makes sense to limit the search to those planets that have stars with a long life time, that are near-by and that if aliens existed on them they could observe Earth transiting the Sun. It am surprised the initial list is as small as 82. It might even encourage us to find ways to detect exoplanets on those stars that do not transit their suns.

http://www.space.com/34611-nasa-cass...nd-finale.html

NASA's Cassini has been a busy spacecraft since it arrived at Saturn in 2004. Some of its key discoveries include seeing active water ice plumes at the moon Enceladus, watching strange storms develop in Saturn's atmosphere and (along with the Europe-led lander Huygens) discovering that the enigmatic moon Titan has lakes and seas just like Earth — but composed of methane and ethane, not water. However, all good things must come to an end and the mission is in its last year of operations. Low on fuel, it will make two daring orbital changes to creep closer to Saturn's rings and the planet before plunging into the planet itself. Here are just a handful of things left on Cassini's "to-do" list.

http://www.space.com/34590-saturn-ri...et-pieces.htmlhttp://www.space.com/34590-saturn-ri...et-pieces.html

The rings of Saturn, Neptune and Uranus are composed of pieces of Pluto-like dwarf planets that strayed too close to the giant worlds long ago, a new study suggests.

Astronomers think that thousands of Pluto-size bodies once dwelled in the Kuiper Belt — the ring of frigid objects beyond Neptune's orbit — shortly after the solar system formed. But things changed about 4 billion years ago, the idea goes: At that time, Jupiter, Saturn, Uranus and Neptune migrated a bit, stirring up both the Kuiper Belt and the main asteroid belt between Mars and Jupiter.

The resulting gravitational jostles sent many objects in these two realms careening toward the inner solar system, causing an era of increased cosmic impacts known as the Late Heavy Bombardment.

The "Late Heavy Bombardment" implies there was an "Early Heavy Bombardment".

Yes, and there was an Early Heavy Bombardment.

For links see https://en.wikipedia.org/wiki/Late_Heavy_Bombardment
and
http://www.space.com/2299-insight-ea...mbardment.html

I also wonder about how the purported extinction of the dinosaurs was done. I wonder what kind of meteorite it was. How large and how widespread was the devastation it caused. All the seems very vague. See http://science.nationalgeographic.co...aur-extinction

I also wonder about how the purported extinction of the dinosaurs was done. I wonder what kind of meteorite it was. How large and how widespread was the devastation it caused. All this remains very vague. What kind of an impact would it have been? How big was the object, a small exomoon, perhaps? The dinosaurs were wiped out in the seas, in the air (flying dinosaurs) and on land. See http://science.nationalgeographic.co...aur-extinction. I also note that National Geographic include a gradualist theory as an alternative.

If I remember what Niles Eldredge said in "Extinction and Evolution" correctly, the dinosaurs were becoming weak long before those meteorites hit the earth. Habitat was being lost because the climate was getting colder. This is not to say the volcanoes or meteorites, whatever deposited the layers containing iridium, did not help make the climate colder.