It’s possible to make a rough estimate of how often planetary systems form by making some basic assumptions. for example, if you assume that the stars we see have been born at random times over the last 10 billion years, then the rate of star formation is simply the number of stars we see divided by 10 billion years. the fraction of stars with detected extrasolar planets is at least 5 %, so this factor can be multiplied in to find the approximate rate of formation of planetary systems.
a) using these assumptions, how often does a planetary system form in our galaxy? (our galaxy contains at least 100 billion stars.)
b) how often does a planetary system form somewhere in the observable universe, which contains at least 100 billion galaxies? (express in seconds)

Create 3 equivalent fractions using the area model for 2/5create equivalent fractions using number lines for 1/2create equivalent fractions using multiplying for .3/4brainliest

What statement about the economy of france is not true? a. paris is a major manufacturing center b. marseille is a busy seaport on the mediterranean coast c. farming is the major activity in the alps. d. world-famous wines are produced in the bordeaux region c. farming is the major activity in the alps

Directions you probably already know that people have different ways to organize their ideas. some people make lists or outlines, some draw pictures, while others may combine these two methods. experiment with different note-taking techniques to find the one which works best for you. one common note-taking technique is webbing. webbing uses the sizes of circles to indicate the importance of items. lines are used to indicate the relationships between items. the example below is based on the information presented in a previous lesson. notice that the circle for "geography is" appears at the center of the web. it has larger than the circles that surround it. the "geography " circle is surrounded by smaller circles of earth's atmosphere, earth's climate, earth's surface. notice the lines that connect these items to the concept of geography. notice that the circles surrounding atmosphere are smaller. also observe that the lines that connect the items and indicate the relationships between the items. webbing will you capture the most important points in your lessons. beginning with lesson two, geographic tools: globes and maps, use webbing to take notes on the important information in this unit. hint: it will be easier to complete this project if you take your notes after completing each lesson.