Why do astronomers consider the space between planets to be a vacuum in comparison with the atmosphere near sea level?

Short Answer

Expert verified
Astronomers consider the space between planets to be a vacuum in comparison with the atmosphere near sea level because of the significant differences in air pressure and particle density. Space has an extremely low particle density, with about 5 particles per cubic centimeter, while Earth's atmosphere near sea level has around 2.7x10^19 particles per cubic centimeter. This distinction between the two is essential in astronomy, as it affects observations, calculations, and predictions of celestial objects and phenomena. The vacuum of space minimizes interference from Earth's atmosphere, leading to clearer images, better detection of cosmic signals, and more accurate modeling of celestial motion.

Step by step solution

01

Understanding Vacuum

A vacuum is a region or space with little to no air or any other matter particles. In other words, it has extremely low pressure and sparse molecular density. In the context of space, the vacuum means that there are very few particles per unit volume compared to what we find in Earth's atmosphere.
02

Atmosphere Near Sea Level vs. Space Vacuum

The atmosphere near Earth's surface, specifically at sea level, has an air pressure of about 101,325 pascals (Pa) or 14.7 pounds per square inch (psi). Air molecules are densely packed in this region, primarily consisting of nitrogen, oxygen, and trace amounts of other gases such as argon, carbon dioxide, and water vapor. On the other hand, space between planets, also known as interplanetary space, has a much lower air pressure and particle density. While not an absolute vacuum, the particle density is so low that it is often considered a vacuum due to the contrast with Earth's atmosphere. The density varies, but it's roughly about 5 particles per cubic centimeter in interplanetary space, whereas near sea level, it's about 2.7x10^19 particles per cubic centimeter.
03

Importance for Astronomers

Astronomers view the space between planets as a vacuum because it affects several aspects of their research and observations: 1. Optical and infrared observations: Earth's atmosphere absorbs and scatters light, which can lead to blurred and distorted images of celestial objects. Observing from space allows astronomers to obtain clearer and more accurate images due to the absence of atmospheric interference. 2. Radio and microwave observations: Signal interference from Earth's atmosphere or ionosphere can hinder the efficient detection of cosmic radio signals from sources such as pulsars or evidence of the cosmic microwave background radiation. Considering space to be a vacuum minimizes signal distortion caused by Earth's atmosphere. 3. Modeling and predicting planetary motion: The virtually negligible density of particles in interplanetary space means that friction and air resistance can be neglected when calculating the motion of celestial bodies and the behavior of spacecraft. This simplifies calculations and improves the accuracy of orbit predictions. So, by comparing the atmosphere near sea level to the space between planets as a vacuum, astronomers can better understand how various factors affect their observations, calculations, and predictions, which in turn helps advance our understanding of the universe.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Study anywhere. Anytime. Across all devices.

Sign-up for free