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The Helix Nebula • NGC 7293
The Helix Nebula • NGC 7293

... tentacles have been observed from ground-based telescopes for decades, but never have they been seen in such detail. They may actually lie in a disk encircling the hot star. The Helix, located 650 light-years away, is one of the closest planetary nebulae to Earth. This glowing gas cloud appears very ...
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 ...
ExamView - es S1 dept final.tst
ExamView - es S1 dept final.tst

... a. lived during long spans of geologic time. b. lived during short spans of geologic time. c. were destroyed by igneous rocks. d. were destroyed by sedimentary rocks. 14. Why is radioactive decay used to determine the absolute age of rocks? a. Radioactive decay cannot be used to determine the age of ...
Talk - Otterbein University
Talk - Otterbein University

... and its luminosity • The more mass a galaxy has the brighter it is  the faster it rotates  the wider the spectral lines are • Measuring rotation speed allows us to estimate luminosity; comparing to observed (apparent) brightness then tells us the distance ...
STAR OF BETHLEHEM
STAR OF BETHLEHEM

... by gravitational disturbances from stars in the neighbourhood towards the Sun. They may be captured by the pull from the planets (mainly Jupiter) into periodic orbits for up to centuries. Eventually they will evaporate. New ones develop near the Sun a tail due to the radiation pressure of the Sun’s ...
Unit 13 The Solar System
Unit 13 The Solar System

... Which group of planets are made of solid rock? a. b. c. d. ...
Lookback Time in Our Everyday Lives
Lookback Time in Our Everyday Lives

... So how long would it really take for aliens in another star system to receive our TV shows? The real boom in TV occurred just about 60 years ago. So, civilizations as far away as 60 light-years are regularly getting our TV programs (not even in reruns yet), and civilizations within 30 light-years h ...
rotation of the Earth
rotation of the Earth

... ancient Greeks were already aware that the Moon would appear in slightly different locations relative to the stars when viewed from different locations on the Earth, and used this effect to accurately estimate its distance from Earth. However, the lack of any parallax between the stars demonstrated ...
XI. Astronomy: Solar-System Debris and Comets
XI. Astronomy: Solar-System Debris and Comets

... gravitational encounter or a collision, but this now seems unlikely. b. Pluto may be simply the largest and one of the nearest objects in the “Kuiper belt”, a reservoir of comets in the outer parts of the Solar System. Triton may have initially been a similar object, subsequently captured by Neptune ...
5a: So, what was wrong with Ptolemy`s model to a contemporary
5a: So, what was wrong with Ptolemy`s model to a contemporary

... sun is clearly influenced by Copernicus’ ideas, but in this model of Tycho’s the earth does not move. Tycho believed that the earth was stationary because he could not observe any parallax of any star. ...
Physics@Brock - Brock University
Physics@Brock - Brock University

... 43. According to the Einstein’s General Theory of Relativity, the stronger is the force of gravity on a clock, the slower is the clock rate. (a) True. (b) False. 44. As a source of light approaches the event horizon an observer at a fixed distance from the event horizon will observe the emitted ligh ...
Chap1-Introduction - Groupe d`astrophysique de UdeM
Chap1-Introduction - Groupe d`astrophysique de UdeM

...  >50% of solar-type stars harbor at least one planet of any mass and with period up to 100 days.  The frequency of gas giants is strongly correlated with the host star metallicity. • No such correlation for low-mass (< 15 ME) planets.  The mass distribution of Super-Earths and Neptune-mass planet ...
Gravity: Motivation • An initial theory describing the nature of the
Gravity: Motivation • An initial theory describing the nature of the

... anomilies (e.g. Venus and Uranus) that need to be addressed. ...
StarWalkKiDS manual en
StarWalkKiDS manual en

... an astronomical event that occurs twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere. As a result, on the day of the solstice, the Sun appears to have reached its highest or lowest annual altitude in the sky above the horizon ...
Deaths of Stars - Chabot College
Deaths of Stars - Chabot College

... Not fusing: Generates no new energy ...
1 Kepler`s Laws of Planetary Motion
1 Kepler`s Laws of Planetary Motion

... created in this simulator, where they are randomly aligned in our solar system. − Animate the simulated planet. You may need to increase the animation rate for very large orbits or decrease it for small ones. − The planetary presets set the simulated planets parameters to those like our solar system ...
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... There is a direct relationship between Cepheid periods of pulsation and their luminosities ...
Section 1 Notes on Stars
Section 1 Notes on Stars

... There is a direct relationship between Cepheid periods of pulsation and their luminosities ...
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Document

... There is a direct relationship between Cepheid periods of pulsation and their luminosities ...
kepler`s laws and newton`s discovery of universal
kepler`s laws and newton`s discovery of universal

... hired the young mathematician Johannes Kepler to help solve a nagging puzzle: Tycho’s precise measurements of the position of Mars, carefully catalogued for over 20 years, were in stark disagreement with the circular-orbit models of both Ptolemy and Copernicus. Following Tycho’s death in 1601, Keple ...
Chapter 2 The Copernican Revolution
Chapter 2 The Copernican Revolution

... For two massive objects, gravitational force is proportional to the product of their masses divided by the square of the distance between them ...
02_LectureOutline
02_LectureOutline

... For two massive objects, gravitational force is proportional to the product of their masses divided by the square of the distance between them ...
bright - TutorPlus
bright - TutorPlus

... depending on their position on the H-R diagram. • Most stars line up along a slightly curved diagonal line called the main sequence. Our Sun is located on the main sequence. • On the main sequence, low mass stars tend to be cooler and less bright whereas high mass stars are hotter, brighter and loca ...
Earth in Space - Learning Outcomes
Earth in Space - Learning Outcomes

... When the Apollo 11 satellite took the first men to the Moon in 1969 its trajectory was very closely monitored. The satellite had a velocity of 5374 m s-1 when 26306 km from the centre of the Earth and this had dropped to 3560 m s-1 when it was 54368 km from the centre of the Earth. The rocket motors ...
Stars Part 1
Stars Part 1

... 108K, other elements can be formed by other fusion reactions. This only works for elements up to the iron-56. At this point, more energy would be consumed ...
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Planetary habitability



Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia. As the existence of life beyond Earth is unknown, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favourable to life's flourishing—in particular those factors that have sustained complex, multicellular organisms and not just simpler, unicellular creatures. Research and theory in this regard is a component of planetary science and the emerging discipline of astrobiology.An absolute requirement for life is an energy source, and the notion of planetary habitability implies that many other geophysical, geochemical, and astrophysical criteria must be met before an astronomical body can support life. In its astrobiology roadmap, NASA has defined the principal habitability criteria as ""extended regions of liquid water, conditions favourable for the assembly of complex organic molecules, and energy sources to sustain metabolism.""In determining the habitability potential of a body, studies focus on its bulk composition, orbital properties, atmosphere, and potential chemical interactions. Stellar characteristics of importance include mass and luminosity, stable variability, and high metallicity. Rocky, terrestrial-type planets and moons with the potential for Earth-like chemistry are a primary focus of astrobiological research, although more speculative habitability theories occasionally examine alternative biochemistries and other types of astronomical bodies.The idea that planets beyond Earth might host life is an ancient one, though historically it was framed by philosophy as much as physical science. The late 20th century saw two breakthroughs in the field. The observation and robotic spacecraft exploration of other planets and moons within the Solar System has provided critical information on defining habitability criteria and allowed for substantial geophysical comparisons between the Earth and other bodies. The discovery of extrasolar planets, beginning in the early 1990s and accelerating thereafter, has provided further information for the study of possible extraterrestrial life. These findings confirm that the Sun is not unique among stars in hosting planets and expands the habitability research horizon beyond the Solar System.The chemistry of life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the Universe was only 10–17 million years old. According to the panspermia hypothesis, microscopic life—distributed by meteoroids, asteroids and other small Solar System bodies—may exist throughout the universe. Nonetheless, Earth is the only place in the universe known to harbor life. Estimates of habitable zones around other stars, along with the discovery of hundreds of extrasolar planets and new insights into the extreme habitats here on Earth, suggest that there may be many more habitable places in the universe than considered possible until very recently. On 4 November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way. 11 billion of these estimated planets may be orbiting Sun-like stars. The nearest such planet may be 12 light-years away, according to the scientists.
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