Crater counting

Crater counting

Terrestrial planets have hard surfaces that can be re-shaped by several different processes: impact cratering, volcanism, erosion, and tectonics. Impact Cratering There are still small chunks of rock orbiting the Sun left over from the formation of the solar system. Some of them have orbits that cross the orbits of the planets and moons. When they get close enough to a planet or moon, they will be pulled in by the large body’s gravity and strike the surface at a speed of at least the escape velocity of the planet or moon, i. At such speeds, the projectile explodes on impact and carves out a round bowl-shaped depression on the surface. This process is impact cratering. How can you distinguish an impact crater from a volcanic crater? Volcano craters are above the surrounding area on mountaintops while the craters from impacts are below the surrounding area with raised rims. The craters on all of the moons except Io, Mercury, and most of the ones on Mars are from impacts.

Asteroid assault on early planets was more like a gentle massage

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This age has been determined with the radioactive dating technique. Meteorites, which are the very components of our planets (through the process of​.

How do scientists find the age of planets date samples or planetary time relative age and absolute age? If carbon is so short-lived in comparison to potassium or uranium, why is it that in terms of the media, we mostly about carbon and rarely the others? Are carbon isotopes used for age measurement of meteorite samples? We hear a lot of time estimates, X hundred millions, X million years, etc. In nature, all elements have atoms with varying numbers of neutrons in their nucleus.

These differing atoms are called isotopes and they are represented by the sum of protons and neutrons in the nucleus. Let’s look at a simple case, carbon. Carbon has 6 protons in its nucleus, but the number of neutrons its nucleus can host range from 6 to 8. We thus have three different isotopes of carbon: Carbon with 6 protons and 6 neutrons in the nucleus, Carbon with 6 protons and 7 neutrons in the nucleus, Carbon with 6 protons and 8 neutrons in the nucleus.

Both carbon and carbon are stable, but carbon is unstable, which means that there are too many neutrons in the nucleus. Carbon is also known as radiocarbon. As a result, carbon decays by changing one proton into a neutron and becoming a different element, nitrogen with 7 protons and 7 neutrons in the nucleus.

7.2: Compostion and Structure of Planets

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The jovian planets are gas giants and consist of Jupiter, Saturn, Uranus and The planet’s surface shows lots of craters, most dating from the age of heavy.

Water ice is not restricted to Earth. Observations of interstellar clouds show that the building blocks of water, hydrogen and oxygen, are some of the most abundant elements in the Universe. The planets in our solar system are formed by a process called accretion , in which dust grains collide with each other and create larger clumps that again collide and so forth.

Because the cloud of gas and dust from which our solar system formed was rich in hydrogen and oxygen, water is very abundant in our solar system. Comet Hyakutake , captured in Comets consist mainly of water ice and most of the water in Earths oceans was delivered from comets during large bombardments early in Earths history. Picture credit: NASA. During the formation of the planets, the temperatures in the inner solar system, close to the Sun, were too high for hydrogen and oxygen to form water molecules.

Therefore, the inner planets like Mercury, Venus, Earth and Mars the so-called terrestrial planets are all composed of rocky materials with a relatively little amount of water. Most of the water in the oceans on Earth originates from cometary impacts after the creation of our planet. Further out in the solar system, where the temperatures were much lower, the water ice remained stable and the planets the so-called gas giants and moons in the outer solar system therefore contain much more water both in their interior and on the surface.

Both Jupiter and Saturn have several large icy moons, all with different characteristics. Two of the most exotic and interesting moons are the Jovian moon Europa and the Saturnian moon Enceladus. The habitability of life as we know it is intimately tied to the presence of liquid water, and this is of course a main cause for investigating the ice in the Solar System.

Planetary and Space Science

On a planet like Earth, as the rock and the water go through cycles and changes, melting and cooling and eroding and accreting, stripped out in wide valleys and stacked up in towering mountains, the natural phenomena of the past leave traces behind in the crust of the planet. By coring out ancient ice, for example, scientists can study the trapped particles and learn about atmospheric conditions millions of years ago.

By studying magnetic minerals embedded in ancient rock, geologists have learned that the magnetic field of the planet reverses poles —about once every , years on average. Scientists can learn a great deal about Earth from the geological layers of its crust, but even more information may be hidden within the rock record.

Sm-Nd dating. R. W. Carlson, “Sm-Nd dating”, in Encyclopedia of Scientific Dating Methods, W. J. Rink and Thompson, J. Springer, in press. Google Scholar.

Metrics details. Reconstruction of the eruption history of an active volcano is necessary to elucidate its volcanic activity and to assess the probability of its volcanic eruption. Yokodake volcano in central Japan is the only active volcano among the Yatsugatake volcano group. It has effused nine lava flows, most of which have not been dated. For this study, we ascertained the eruption ages of the latest lava Y9 and second most recent lava Y8 using radiocarbon 14 C , thermoluminescence TL , and paleomagnetic dating methods.

Results revealed the eruption ages of the two lava flows and the recent eruption history of Yokodake volcano. Yokodake volcano effused its Y8 lava flow at ca. Understanding the latest activities of an active volcano in terms of their eruption styles, frequencies, and vent locations is particularly important for assessing risks of future volcanic activity.

Cataclysm No More: New Views on the Timing and Delivery of Lunar Impactors

One of the pressing questions about meteorites is what their Parent Planets were like – how large they were, and how evolved internally and externally. Part of answering this question involves knowing about the Ages of meteorites and ideally the planetary objects they came from. We do the measurement by chemically separating the parent and daughter elements from our sample meteorites, and examining the ratios of the Uranium and Lead isotopes in the sample via a technique called Mass Spectrometry.

Studying the layers of Earth’s crust, scientists have created a “Geological Orrery” to measure planetary motions dating back hundreds of.

Research in the prehistory of the sun helps us compare the circumstances of the birth of the sun with those of other stars in our galaxy, setting the existence of the sun, the Earth and humans more firmly within the broader context of the billions of stars and planets and possibly other lifeforms that exist in the Milky Way. Recent historical events have been recorded by the writings of historians.

Going back further in time, though, we have to rely on other methods to date events. One of the main tools to achieve this is radioactivity. Radioactive nuclei, by definition, decay as time passes by emitting energetic particles that can be very dangerous to living organisms. The rate at which they decay is defined by their half-life, which is the time it takes for half of the original nuclei to disappear.

A famous example is carbon , which has a half-life of 5, years. If the recovered bones of a human contain roughly half the amount of carbon present in the biosphere, that individual must have died 5, years ago.

The Space & Beyond Blog

Over the last couple of days I have fallen down a research rabbit hole — I began with a question about clay minerals on Mars and find myself, today, writing about the history of major impact basins on the Moon. The trail that led me here has to do with geologic time scales — the stories that geologists tell about the major events that happened in the history of a planet. I will climb back out of the rabbit hole eventually with lots of good stories about the geology of many different planets, but I’m going to have to tell those stories bit by bit.

It all begins, appropriately, with the history of impact basins on the Moon. I think that’s appropriate because the Moon is where the study of planetary geology started, even before the Space Age.

During the formation of the planets, the temperatures in the inner solar system, close to the Sun, were too high for hydrogen and oxygen to form water molecules​.

These small rocky worlds are thought to have been born in a disc of dust and gas that surrounded the Sun. As time went by, the dust grains snowballed into larger and larger rocks and boulders. About 4. The terrestrial planets we see today are the survivors of a prolonged, chaotic period of colossal impacts which left their surface imprints in the form of giant basins and craters. How can we piece together a planet’s history since its formation?

On Earth, the geological timeline is quite easy to determine, since we can analyse the rocks and minerals in laboratories. On Mars, it is much more difficult to piece together the planet’s history. With the exception of more than Martian meteorites which have been discovered on Earth, there are no samples of materials from the Red Planet to study. Limited rock and soil analysis has been undertaken by spacecraft and rovers that have landed on Mars in recent years, but no radiometric dating of the samples has been possible.

Given the current lack of samples acquired from known locations on Mars, planetary scientists have to estimate the age of the surface by counting the number of visible craters: a higher number and density of craters indicates older terrain. Complications arise because Mars has experienced extensive volcanism, as well as erosion by glaciers, wind and running water, and widespread deposition of sediments that may bury older craters.

Based on the presence of the largest impact structures, the highest crater densities and the impact history of the inner Solar System, the southern highlands of Mars represent the oldest crust. They are believed to have formed prior to 3. The more sparsely cratered northern plains are younger, since they have fewer and smaller craters, having formed after the end of the great bombardment.

Dating the Moon’s basins

The fact that there are two distinct kinds of planets—the rocky terrestrial planets and the gas-rich jovian planets—leads us to believe that they formed under different conditions. Certainly their compositions are dominated by different elements. Let us look at each type in more detail. On Earth, both hydrogen and helium are gases, so Jupiter and Saturn are sometimes called gas planets.

Earth, Planets and Space volume 72, Article number: () Cite this The radiocarbon (14C) dating is frequently used for eruption age.

Although researchers have determined the ages of rocks from other planetary bodies, the actual experiments—like analyzing meteorites and moon rocks—have always been done on Earth. Now, for the first time, researchers have successfully determined the age of a Martian rock—with experiments performed on Mars. The work, led by geochemist Ken Farley of the California Institute of Technology Caltech , could not only help in understanding the geologic history of Mars but also aid in the search for evidence of ancient life on the planet.

However, shortly before the rover left Earth in , NASA’s participating scientist program asked researchers from all over the world to submit new ideas for experiments that could be performed with the MSL’s already-designed instruments. Farley, W. Keck Foundation Professor of Geochemistry and one of the 29 selected participating scientists, submitted a proposal that outlined a set of techniques similar to those already used for dating rocks on Earth, to determine the age of rocks on Mars.

Findings from the first such experiment on the Red Planet—published by Farley and coworkers this week in a collection of Curiosity papers in the journal Science Express —provide the first age determinations performed on another planet. The paper is one of six appearing in the journal that reports results from the analysis of data and observations obtained during Curiosity’s exploration at Yellowknife Bay—an expanse of bare bedrock in Gale Crater about meters from the rover’s landing site.

The smooth floor of Yellowknife Bay is made up of a fine-grained sedimentary rock, or mudstone, that researchers think was deposited on the bed of an ancient Martian lake.

Ice on other planets and moons

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dating rocks on Earth, to determine the age of rocks on Mars. Findings from the first such experiment on the Red Planet—published by Farley.

How do we know the age of the surfaces we see on planets and moons? If a world has a surface as opposed to being mostly gas and liquid , astronomers have developed some techniques for estimating how long ago that surface solidified. Note that the age of these surfaces is not necessarily the age of the planet as a whole. On geologically active objects including Earth , vast outpourings of molten rock or the erosive effects of water and ice, which we call planet weathering, have erased evidence of earlier epochs and present us with only a relatively young surface for investigation.

One way to estimate the age of a surface is by counting the number of impact craters. This technique works because the rate at which impacts have occurred in the solar system has been roughly constant for several billion years. Thus, in the absence of forces to eliminate craters, the number of craters is simply proportional to the length of time the surface has been exposed.

This technique has been applied successfully to many solid planets and moons Figure 1. Figure 1. Bear in mind that crater counts can tell us only the time since the surface experienced a major change that could modify or erase preexisting craters. Estimating ages from crater counts is a little like walking along a sidewalk in a snowstorm after the snow has been falling steadily for a day or more.

PLANET X Nibiru Effects on planets of the Galaxy – Nibiru Planet X News Update 2018


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