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What makes a planet habitable?
What makes a planet habitable?

... 20EUV (4.13 Gyr ago): subsolar obstacle distance 12.7REarth N+ion pick up loss rate ~2 ×1030 s-1 Total loss of nitrogen would result in an equivalent amount of ≤ 20 bar during ~ 50 Myr Simulations indicate that the atmosphere should have been protected more efficiently most likely due to higher carb ...
PH607 – Galaxies 2
PH607 – Galaxies 2

... formation event a few million years ago. The existence of these relatively young (though evolved) stars there was of a surprise to experts, who would have expected the tidal forces from the central black-hole to prevent their formation. They are much too young to have migrated far, but it seems even ...
ASTR-100 - Jiri Brezina Teaching
ASTR-100 - Jiri Brezina Teaching

... called hemispheric seasons. The changing distance planet – Sun, due to the planet’s elliptical orbit, influences the whole planet’s temperature; the resulting seasons are called global seasons (see below). Looking ‘down’ on the Earth’s North Pole, both its axial rotation and revolution (orbiting) ar ...
Publication - Centre for Star and Planet Formation
Publication - Centre for Star and Planet Formation

General exercise model answer Exercise 1 page 90 to 93 Question
General exercise model answer Exercise 1 page 90 to 93 Question

... 1. Due to rotation of the Earth around its axis. 2. Due to revolution of the Earth around the Sun. Question (8) - The element is a metal if: o It has lustre and conducts heat and electricity. (malleable and ductile) - The element is non-metal if: o It has no lustre and bad conductor of heat. Exercis ...
Astronomy 3020: Cosmology Samples for Exam 3
Astronomy 3020: Cosmology Samples for Exam 3

... a) the fusion of four hydrogen into a single helium plus two positrons and energy through several steps. b) the fusion of three helium into a single carbon through several steps. c) the fusion of two protons into a helium. d) the emission of electromagnetic radiation due to a transition from one ene ...
1 History of Astronomy - Journigan-wiki
1 History of Astronomy - Journigan-wiki

... heavens is not like a divine animal but like a clock (and anyone who believes a clock has a soul gives the work the honor due to its maker) and that in it almost all the variety of motions is from one very simple magnetic force acting on bodies, as in the clock all motions are from a ...
Apparent magnitude
Apparent magnitude

Scale in the Solar System
Scale in the Solar System

Student 1
Student 1

... Barnard’s star. An ancient Red Dwarf. Barnard's Star is a very low-mass red dwarf star about six light-years away from Earth in the constellation of Ophiuchus. Barnard's Star is the fourth-closest known individual star to the Sun, after the three components of the Alpha Centauri system. Despite its ...
Grade 9 Applied
Grade 9 Applied

... If the answer is true write T. If the answer is false write F. 26. _____ A nebula is a cloud of dust and gas, the birthplace of stars. 27. _____ Distances between the planets are measured in astronomical units. 28. _____ There is a black hole very close to the Earth. 29. _____The Milky Way is an ell ...
Characteristics of Stars
Characteristics of Stars

... • White dwarfs are about the size of Earth • Neutrons stars are only about 20 km in ...
The Life Cycle of Stars
The Life Cycle of Stars

... exhausted its ability to fuse other elements like carbon and oxygen, it will become a red giant and expand in size to envelope the Earth. And surprisingly, the larger the mass of the star, the quicker it burns its fuel sources and the shorter its lifespan. Also see and read about Hubble Space Telesc ...
A Giant Planet Around a Metal-poor Star of Extragalactic Origin
A Giant Planet Around a Metal-poor Star of Extragalactic Origin

Sirius Astronomer - Orange County Astronomers
Sirius Astronomer - Orange County Astronomers

... last year and President this year. For those of you that know me, I'm not a very talkative person, especially when it comes to written correspondence. I'm usually brief and to the point. So, if this letter seems short, have a good laugh because it’s probably twice as long as my usual letters. OCA is ...
Linking Asteroids and Meteorites through Reflectance Spectroscopy
Linking Asteroids and Meteorites through Reflectance Spectroscopy

... Sun out to the Sun’s orbit • Mass-to-Light ratio of our Sun is 1 solar mass per solar luminosity • So most matter is dimmer than the Sun ...
Constellations Reading
Constellations Reading

The definition of a planet - the Solar System Support Pages
The definition of a planet - the Solar System Support Pages

astronomy
astronomy

Transits of extrasolar moons around luminous giant planets
Transits of extrasolar moons around luminous giant planets

... to follow a universal formation law (Canup & Ward 2006). We need to keep in mind, though, that these planets orbit the outer regions of the solar system, where stellar illumination is negligible for moon formation (Heller & Pudritz 2015a). However, many giant exoplanets are found in extremely short- ...
New Indivisible Planetary Science Paradigm J. Marvin Herndon
New Indivisible Planetary Science Paradigm J. Marvin Herndon

... primary atmospheres. But the inner planets originated from giant gaseous protoplanets and their massive, primordial gases. How were the gases lost? A brief period of violent activity, the T-Tauri phase, occurs during the early stages of star formation with grand eruptions and super-intense “solar-wi ...
SOLAR eclipse LUNAR eclipse
SOLAR eclipse LUNAR eclipse

Unit 1
Unit 1

... the star, and back again – To passengers on the ship, it only takes 20 years for the round-trip! ...
intergalactic move
intergalactic move

... or dust. The stars in elliptical galaxies are mostly very old. Some galaxies are spiral galaxies, with curved arms wrapped around a bright central core or have a bar of stars across the centre, with arms attached at either end. Some galaxies have no recognisable shape but our own Milky Way galaxy is ...
Introduction to Stars ppt
Introduction to Stars ppt

... M-Sun star has 30 times more H than the Sun, but burns it with a luminosity that is 30,000 times greater. It’s lifetime is 30/30,000 = 1/10,000 as long as the Sun – corresponding to a lifetime of only a few million years. This is a very short time, cosmically speaking. This is one reason why massive ...
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Rare Earth hypothesis



In planetary astronomy and astrobiology, the Rare Earth Hypothesis argues that the origin of life and the evolution of biological complexity such as sexually reproducing, multicellular organisms on Earth (and, subsequently, human intelligence) required an improbable combination of astrophysical and geological events and circumstances. The hypothesis argues that complex extraterrestrial life is a very improbable phenomenon and likely to be extremely rare. The term ""Rare Earth"" originates from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist, both faculty members at the University of Washington.An alternative view point was argued by Carl Sagan and Frank Drake, among others. It holds that Earth is a typical rocky planet in a typical planetary system, located in a non-exceptional region of a common barred-spiral galaxy. Given the principle of mediocrity (also called the Copernican principle), it is probable that the universe teems with complex life. Ward and Brownlee argue to the contrary: that planets, planetary systems, and galactic regions that are as friendly to complex life as are the Earth, the Solar System, and our region of the Milky Way are very rare.
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