This article was originally published on Conversation. The post was contributed by Space.com Expert Voices: Editorial and Insights.
Adam Burgasser He is a professor of astronomy and astrophysics at the University of California, San Diego, and an observational astrophysicist who researches the most fascinating stars, brown dwarfs, and exoplanets.
Measuring the ages of planets and stars helps scientists understand when they formed and how they change — and, in the case of planets, whether Life has had time to evolve.
Unfortunately, it is difficult to measure the age of the objects in them space.
Stars like the sun Maintaining himself Brightness, temperature and volume for billions of years. Planet characteristics Such as temperature They are often determined by the star they orbit rather than their age and evolution.
Determining the age of a star or planet can be as difficult as guessing the age of a person who looks exactly the same from childhood to retirement.
Guess the age of the star
Luckily, The stars change subtly In brightness and color more time. Through very precise measurements, astronomers can compare these measurements to the star Mathematical models Which predicts what happens to stars As they get older the age estimate goes from there.
The stars not only glow, they also rotate. over time, Their rotation slows down, similar to the way a spinning wheel slows down when exposed to friction. By comparing the rotation speeds of stars of different ages, astronomers were able to do this Establish mathematical relationships for the ages of starsThis method is known as Rotation science.
The star’s rotation also generates powerful energy magnetic field It produces magnetic activity, e.g Star flares – Powerful explosions of energy and light that occur on the surfaces of stars. The steady decline in a star’s magnetic activity can also help estimate its age.
The most advanced method for determining the ages of stars is called AstroseismologyOr the vibration of a star. Astronomers study vibrations on the surfaces of stars caused by waves traveling through their interior. Young stars have different vibrational patterns than old stars. Using this method, Astronomers have estimated The sun is 4.58 billion years old.
Piecing together the age of the planet
In the Solar System, Radionuclides It is the key to planetary history. This is special Atoms Which releases energy slowly over a long period of time. Like natural clocks, radionuclides help scientists determine the ages of all kinds of objects, from… Rocks to Bones And Pottery.
Using this method, scientists determined that it was the oldest known meteor He is 4.57 billion yearsIt is almost identical to astronomical seismic measurements of the Sun 4.58 billion years ago. Oldest known rocks Land They have slightly younger ages 4.40 billion years. Likewise, the soil was restored from the moon During the Apollo missions it was The age of radionuclides is up to 4.6 billion years.
Although studying radionuclides is a powerful way to measure planetary ages, it usually requires having a rock on hand. Normally, astronomers only have an image of a planet they pass by. Astronomers often determine the ages of rocky space objects such as Mars Or the moon Count their holes. Older roofs have more potholes than newer roofs. But corrosion caused by water and wind Cosmic rays Lava flows from volcanoes can erase evidence of past impacts.
Aging techniques don’t work on giant planets like… Jupiter Which have deeply buried surfaces. However, astronomers can estimate their ages by… Count the craters on their moons Or study Distribution of certain classes of meteorites Scattered out, which is consistent with radionuclides and drilling methods Rocky planets.
We cannot yet directly measure the ages of planets outside our solar system using current technology.
How accurate are these estimates?
Our solar system provides the best check for accuracy, as astronomers can compare the ages of radionuclides for rocks on Earth, the Moon, or Asteroids To the era of solar astronomy, these match up very well.
Stars in groups like chandelier or Omega Centauri They are all thought to have formed at about the same time, so estimates of the ages of individual stars in these clusters should be the same. In some stars, Astronomers can discover Radionuclides such as uranium — a heavy metal found in rocks and soil — in its atmosphere, which have been used to verify ages in other ways.
Astronomers believe that planets are roughly the same age as their host stars, so improving methods for determining a star’s age will help determine a planet’s age as well. By studying subtle clues, it is possible to make an educated guess at the age of a fixed star.
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