There are different methods for measuring the distances at which heavenly objects are located. Each method is useful for measuring a certain range of distances. In Unit 2 “Distancias I. Galaxias”, you can see how distances to the nearest stars in our galaxy are measured. Here we will look at other methods used to measure distances to more distant objects, such as quasars.

Introduction

Does the brightness of stars help us to determine their distance? And galaxies, how can we measure their distance from us? What are quasars and how far away are they? In this Didactic Unit you will find answers to all these questions and many others.

Download here the INTRODUCTION to this Didactic Unit.

Activities

Do you want to calculate the brightness of a quasar and see how it changes over time? You can do it in the activity below, using real images of the quasar 3C454.3 obtained with the Liverpool Telescope.

• Download the ACTIVITY GUIDE.
• Download the images of the QUASAR you are going to work with.
• Download this SPREADSHEET to write down your measurements.
• If you haven’t already done so, download the software (PeterSoft) to view and analyse the images.

Remember you can also obtain your own images of the planets in  “Quiero Observar” and make new measurements and investigations.

Activity Data

Concepts: Measuring “large” distances in the Universe. Cepheids. The Doppler effect and the redshift. Quasars. Magnitude of a star.

Tools to learn to use: Brightness measurement. Differential photometry.

Estimated time: 3 hours.

Authors: Oswaldo González, Nayra Rodríguez, Alfred Rosenberg, Inés Bonet.

Materials for educators: Teacher’s guide.