GOLDSCHMIDT CONFERENCE
Planets which are tilted on their axis, like Earth, are more capable of evolving complex life. This finding will help scientists refine the search for more advanced life on exoplanets. This NASA-funded research is presented at the Goldschmidt Geochemistry Conference.
Since the first discovery of exoplanets (planets orbiting distant stars) in 1992, scientists have been looking for worlds which might support life. It is believed that to sustain even basic life, exoplanets need to be at just the right distance from their stars to allow liquid water to exist; the so-called ‘Goldilocks zone’. However, for more advanced life, other factors are also important, particularly atmospheric oxygen.
Oxygen plays a critical role in respiration, the chemical process which drives the metabolisms of most complex living things. Some basic life forms produce oxygen in small quantities, but for more complex life forms, such as plants and animals, oxygen is critical. Early Earth had little oxygen even though basic life forms existed.
The scientists produced a sophisticated model of the conditions required for life on Earth to be able to produce oxygen. The model allowed them to input different parameters, to show how changing conditions on a planet might change the amount of oxygen produced by photosynthetic life.
Lead researcher Stephanie Olson (Purdue University) said “The model allows us to change things such as day length, the amount of atmosphere, or the distribution of land to see how marine environments and the oxygen-producing life in the oceans respond.”
The researchers found that increasing day length, higher surface pressure, and the emergence of continents all influence ocean circulation patterns and associated nutrient transport in ways that may increase oxygen production. They believe that these relationships may have contributed to Earth’s oxygenation by favouring oxygen transfer to the atmosphere as Earth’s rotation has slowed, its continents have grown, and surface pressure has increased through time.
“The most interesting result came when we modelled ‘orbital obliquity’ – in other words how the planet tilts as it circles around its star,” explained Megan Barnett, a University of Chicago graduate student involved with the study. She continued “Greater tilting increased photosynthetic oxygen production in the ocean in our model, in part by increasing the efficiency with which biological ingredients are recycled. The effect was similar to doubling the amount of nutrients that sustain life.”
Earth’s sphere tilts on its axis at an angle of 23.5 degrees. This gives us our seasons, with parts of the Earth receiving more direct sunlight in summer than in winter. However, not all planets in our Solar System are tilted like the Earth: Uranus is tilted at 98 degrees, whereas Mercury is not tilted at all. “For comparison, the Leaning Tower of Pisa tilts at around 4 degrees, so planetary tilts can be quite substantial”, said Barnett.
Dr Olson continued “There are several factors to consider in looking for life on another planet. The planet needs to be the right distance from its star to allow liquid water and have the chemical ingredients for the origin of life. But not all oceans will be great hosts for life as we know it, and an even smaller subset will have suitable habitats for life to progress towards animal-grade complexity. Small tilts or extreme seasonality on planets with Uranus-like tilts may limit the proliferation of life, but modest tilt of a planet on its axis may increase the likelihood that it develops oxygenated atmospheres that could serve as beacons of microbial life and fuel the metabolisms of large organisms. The bottom line is that worlds that are modestly tilted on their axes may be more likely to evolve complex life. This helps us narrow the search for complex, perhaps even intelligent life in the Universe”.
Timothy Lyons, Distinguished Professor of Biogeochemistry in the Department of Earth and Planetary Sciences at the University of California, Riverside commented:
“The first biological production of oxygen on Earth and its first appreciable accumulation in the atmosphere and oceans are milestones in the history of life on Earth. Studies of Earth teach us that oxygen may be one of our most important biosignatures in the search for life on distant exoplanets. By building from the lessons learned from Earth via numerical simulations, Olson and colleagues have explored a critical range of planetary possibilities wider than those observed over Earth history. Importantly, this work reveals how key factors, including a planet’s seasonality, could increase or decrease the possibility of finding oxygen derived from life outside our solar system. These results are certain to help guide our searches for that life”.
Professor Lyons was not involved in this work, this is an independent comment
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Models do nothing more than the assumptions of the programmers who made it. That is not evidence.
The reason models tend to work in physics and engineering is the abundance of high quality data already accumulated by researchers. Climate science is almost all assumptions. Practitioners know it’s all backdrop to a new world totalitarian order. So there has been no new ideas in 40yrs.
So apparently they say that life only requires some good water based chemistry on a planet with a bit of a tilt.
Maybe so but why does so much of life on this planet have biological cycles that are linked to our rather overlarge, moon?
Such lunar cycles may not be required for life to start, but can life go on and evolve fast enough without that Lunar tidal rhythm which happens constantly? Lunar affects that pulls oceans about bringing tides that run up and down shorelines regularly, lunar effects that affect the atmosphere and it’s movements and thus affects the weather.
The moon affects life?
_https://www.nhm.ac.uk/discover/how-does-the-moon-affect-life-on-earth.html_
How does the Moon affect life on Earth? By Kerry Lotzof
“From weeping trees to teeth stronger than Kevlar, senior curator Dr Tom White sheds some light on a few of the fascinating, unnoticed ways the Moon shapes the course of life on Earth.
‘The Moon has been up there as long as evolution has been taking place, and lunar rhythms are embedded in the life cycles of many organisms,’ Tom says.’The challenge is working out when the Moon truly is a factor and what is merely myth and legend.'”
_https://core.ac.uk/display/149556979_
“Does the Lunar Cycle Affect Reef Fish Catch Rates?…
The lunar effect in the bottom longline fishery differed between species, with increased CPUE consistently predicted to occur near the new moon for Red Grouper and to take place proximal to the full moon for Tilefish. Red Grouper captured with vertical line gear had two CPUE increases predicted around the waxing and waning lunar phases. Inconsistencies in lunar effect between gear types for Red Grouper were present, possibly due to different mechanisms affecting CPUE.”
_https://academic.oup.com/beheco/article/24/1/53/2261367
“The responses to the lunar cycle can not be generalized across taxonomic group, but instead are highly species specific and relate directly to the species’ ecology. The primary reasons for changes in amphibian behavior in response to the lunar cycle appear to be temporal synchronization of breeding and predator avoidance. Responses to changes in prey availability, facilitation of visual signalling and use of lunar cues in navigation and homing are less prevalent but merit further investigation.”
_https://core.ac.uk/display/15963836
Lunar cycles in diel prey migrations exert a stronger effect on the diving of juveniles than adult Galapagos fur seals. By M Horning and Fritz Trillmich.
_https://link.springer.com/article/10.1023/A:1017088504226
Marine Animal Behaviour In Relation To Lunar Phase by E. Naylor
_https://www.sciencedirect.com/science/article/pii/S0960982208008658
Human Responses to the Geophysical Daily, Annual and Lunar Cycles by Russell G.Foster Till Roenneberg
There are quite a few more.
If you want to find another habitable planet read the books “Rare Earth” and “the Privileged Planet”. The latter tells you exactly what to look for to find a planet capable of housing metazoans. But that isn’t sufficient for life. Life is more than just add water and give it a place to grow. Only if you wrongly assume that nature put life here would you think that just finding the right planet solves the problem.
Is there even a single shred of evidence that complex life is to be found on any planet other than our earth? This is not science but science fiction.
Roswell, 1947. Or do you really think that intelligence officers confused a weather balloon for a space craft?
All swans are white…………until they’re not
Models. They found nothing. They played video games all night.
It’s not clear why a planet whose axis of rotation is tilted relative to the axis of revolution around its star would be more favorable to the development of life, or oxygen in its atmosphere. It is true that, for the Earth with its size and distance from the sun, that the 23.5-degree tilt enables life to exist farther from the Equator than would ordinarily be possible with a non-tilted axis (an earth without seasons). In temperate regions (about 35 to 60 degrees latitude), the current tilt enables the favored (spring/summer) hemisphere to receive enough sunlight to prevent water from freezing for several consecutive months, providing a frost-free and ice-free growing season which would not occur at those latitudes on a season-less earth.
But what about a hypothetical planet with an Earth-like chemical composition which was slightly closer to its star than Earth (or the same distance from a stronger star)? For such a planet, water could remain liquid farther from its equator even without a tilted axis, and life in its equatorial regions could be better adapted to warm water, while life in its middle latitudes to cooler water.
For a hypothetical Earth-like planet slightly farther from its star than Earth (or with a weaker star than the sun), liquid water would be limited to a narrow band around its equator, and any tilt in its axis would make its “tropics” colder on average, and possibly unable to support life.
An extreme tilt such that of Uranus would be extremely unfavorable to the development of life, regardless of distance to the star. For example, an axis tilt of exactly 90 degrees would result in polar regions with the star nearly at the zenith part of the year, and total darkness another part of the year, while equatorial regions would receive very strong insolation twice a year (when the equator faced the star), and very weak insolation twice a year (with the equator perpendicular to the line from the planet to the star). This extreme variability of climate with seasons would probably make most regions either too hot or too cold for life at various times all over the planet.
In the search for life on other planets outside our solar system, the main factors to consider are the intensity of radiation from the star, distance of the planet from the star, gravity of the planet (which affects its ability to hold an atmosphere), and presence of oxygen in its atmosphere and liquid water on the surface. The tilt of the axis of rotation relative to the plane of revolution (ecliptic) is a relatively minor factor.
There will never be additional “intelligent” life discovered. We only know of angels and man. All intelligent life is right here. I know this without hesitation. Its as plain as the nose on your face.
Intelligent life did not evolve from un-intelligent.