Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Radio Telescopes

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now
Radio Telescopes

The collection of experimental data is one of the keystones in astrophysics as it is crucial to studying systems that we are not able to replicate on the earth. Although the first telescope was developed by Galileo Galilei at the beginning of the 17th century, the idea that astrophysics needs to measure much more data than what we see with our eyes is relatively new.

It is in this context that specific types of telescopes were developed to gather incoming radiation in many different frequencies (such as gamma rays, x-rays, radio waves, etc.). The relevance of radio telescopes comes from the fact that radio waves constitute a type of radiation that is more efficiently transmitted through the universe and corresponds to specific large objects like black holes or the nuclei of galaxies.

What are radio waves?

Radio waves are electromagnetic waves with wavelengths of more than 1 millimetre, the largest wavelength in the whole electromagnetic spectrum. They are produced by the largest objects in the universe, and it is crucial to collect and study them.

Sources in the universe

The main source of information about the universe is electromagnetic radiation. There is a simple physical connection between this radiation and the material content we observe in the universe: larger objects are associated with larger wavelength radiation and smaller objects with shorter wavelength radiation.

This does not mean that small or large systems do not emit other kinds of radiation but that their most intense emission is of the types mentioned above. This is why the collection of radio waves gives us information about large objects in the universe. The main sources in the universe are the following:

  • Black holes: these are objects formed by an accumulation of a very large amount of mass in a small region, which do not allow anything to escape their gravitational attraction, not even light. Their properties can be studied thanks to the processes they cause in their surroundings, some of which are emissions in the radio region.
  • Galaxies: these are associations of millions of stars that may orbit a nucleus. The collective effects observed may be associated with scales so large that they can only be studied in the radio region.
  • Supernovas: these explosive events, which constitute the death of stars, emit in all frequencies, but due to the characteristic size of these events, there is a relevant emission in the radio region.
  • Quasars: these supermassive black holes are the nucleus of a certain galaxy. We have already mentioned galaxies and black holes as independent objects that can emit radio radiation. A quasar is a black hole that concentrates a huge amount of the mass of a galaxy and, as such, emits radio radiation more intensely than smaller black holes or galaxies that do not have a black hole in their nucleus.
  • Cosmic microwave background: a remnant spectrum of radiation from the first stages of the universe, which mainly peaks in the microwave region (the second largest-wavelength region). However, there is also plenty of relevant information in the radio region that allows us to study the origin of the universe.

Transmission and extinction

The collection of astronomical data happens after the radiation has travelled very large distances between the sources and our telescope, which cannot be very far from the earth (because of time and technological constraints). If, however, we know how to correct the bias and issues produced by observing from a large distance, there should be no problem with using these measurements. However, there is an unavoidable problem associated with all kinds of radiation: extinction.

Extinction is the phenomenon by which electromagnetic radiation is lost due to the interaction with astronomical structures between the source of emission and the observer.

It turns out that this effect obeys a similar rule to that for the association of wavelengths with sizes: smaller wavelength radiation interferes more with smaller objects while larger wavelength radiation interferes more with bigger objects. Since most of the structures in the universe consist of components of small size, extinction is a phenomenon that affects mainly smaller wavelength radiation. In other words, radio radiation is the most faithfully transmitted radiation in the universe.

What are single-dish radio telescopes?

Single-dish radio telescopes are the most widely used devices to gather information that comes from the universe in the form of radio waves. Usually, they consist of a single large dish necessary to capture the waves in the desired range.

Parts and functioning

The main parts of a single-dish radio telescope are the following:

  • The dish or reflector: like most modern telescopes, radio telescopes are reflecting telescopes where the dish is in charge of collecting the incoming information and reflecting it towards another part. Due to the characteristic wavelength of radio waves, the dish of radio telescopes is very large (more than 100 metres in diameter), which means that they have a good ability to collect radiation.
  • The antenna: this is the part towards which the radiation is reflected and which is in charge of collecting and transmitting it to the devices that carry out the analysis of the information.
  • The amplification and analysis system: this is the part where the information is amplified in intensity if needed and analysed to extract conclusions about the spectrum properties.

The reason we refer to single-dish radio telescopes is that, usually, radio telescopes are part of a larger complex that includes multiple single-dish radio telescopes. These complexes allow us to amplify further the collecting power by combining the telescopes instead of building a huge dish of several hundreds of metres (or even kilometres). The first image ever detected of what seems to be a black hole was obtained thanks to seven radio telescopes located all around the earth, which allowed to amplify their power.

Radio Telescopes. Black hole. Radio telescopes. StudySmarterFigure 1. First image of a black hole. Source: Event Horizon Telescope, Wikimedia Commons (CC BY 4.0).

Advantages and disadvantages

The radio telescopes have many advantages because the radiation they measure is subject to almost no extinction. The size of the telescopes ensures a great collecting power and a huge capacity of resolution, allowing to separate different objects at very large distances. The main disadvantage is that the economic cost of these telescopes is high, but the development of telescope complexes has brought those costs down.

Radio Telescopes. Radio telescopes. StudySmarterFigure 2. Very Large Array (VLA) of radio telescopes. Source: Hajor, Wikimedia Commons (CC BY-SA 2.0).

Radio Telescopes - Key takeaways

  • Radio waves are the radiation with the largest wavelength in the whole electromagnetic spectrum.
  • Radio radiation provides information about large systems, such as galaxies, black holes, quasars, or the cosmic microwave background.
  • Radio waves constitute the radiation that is transmitted most faithfully through the universe, which makes radio telescopes very useful.
  • Single-dish radio telescopes are very large reflecting telescopes that can collect a lot of radiation in the radio region. They can be combined to enhance their power.

Frequently Asked Questions about Radio Telescopes

Radio telescopes collect radiation from the radio region thanks to a single dish that reflects it to an antenna that processes the signal and sends it to be analysed. Several radio telescopes can be combined to enhance their power.

Radio telescopes are not based on visual input, which means that they measure radiation in different regions of the electromagnetic spectrum.

A radio telescope is a device that collects radiation from the universe with wavelengths larger than 1 mm.

Like the majority of modern telescopes, radio telescopes are usually reflecting telescopes.

The size of their dish usually exceeds 100 metres in diameter.

Final Radio Telescopes Quiz

Question

Select the correct statement:

Show answer

Answer

Astrophysics uses radiation from all frequencies.

Show question

Question

Select the correct statement:

Show answer

Answer

Some sources of radio radiation are black holes, galaxies, and quasars.

Show question

Question

Select the correct statement:

Show answer

Answer

Radio waves are less dimmed than any other radiation due to extinction.

Show question

Question

Select the correct statement:

Show answer

Answer

Radio telescopes are usually reflecting telescopes.

Show question

Question

Select the correct statement:

Show answer

Answer

Radio telescopes have to be large due to the characteristic wavelength of radio waves.

Show question

Question

Who invented the first telescope?

Show answer

Answer

Galileo Galilei.

Show question

Question

Which astronomical objects usually emit in the radio region?

Show answer

Answer

Large objects.

Show question

Question

What are quasars?

Show answer

Answer

Supermassive black holes that are the nucleus of a galaxy.

Show question

Question

What is cosmic background radiation?

Show answer

Answer

Remnant radiation that gives information of the origin of the universe.

Show question

Question

Do supernovas only emit in the radio region?

Show answer

Answer

No, they emit in all frequencies.

Show question

Question

What is the main difficulty in collecting data from the universe?

Show answer

Answer

Extinction.

Show question

Question

What is the approximate size of radio telescopes?

Show answer

Answer

More than 100 metres of diameter.

Show question

Question

What technique is used to prevent building huge radio telescopes?

Show answer

Answer

Using several standard telescopes and combining their data.

Show question

Question

What is the main advantage of measuring radio radiation?

Show answer

Answer

It is the radiation that is less dimmed due to extinction.

Show question

Question

Towards which object is the data in a single-dish radio telescope reflected?

Show answer

Answer

Towards the antenna.

Show question

60%

of the users don't pass the Radio Telescopes quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Just Signed up?

Yes
No, I'll do it now

Sign up to highlight and take notes. It’s 100% free.