How is it possible that we can see planets in the night sky even though they do not produce their own light?

Because planets do not have nuclear fusion, they do not produce their own light. Instead, they shine with light reflected from a star. When we see planets in the night sky, such as Venus, the so-called “Evening Star,” we’re seeing reflected sunlight.

How does the Doppler technique allow us to infer the existence of exoplanets around a distant star?

Doppler spectroscopy is used to detect the periodic velocity shift of the stellar spectrum caused by an orbiting giant planet. (This method is also referred to as the radial velocity method.) The minimum detectable planet mass gets smaller in inverse proportion to the planet’s distance from the star.

How can scientists identify these exoplanets knowing that planets do not have their own light to emit?

Exoplanets that can most reliably be seen by telescopes are large (like Jupiter) and very hot, so that they give off their own infrared radiation, which can be detected by telescopes and used to distinguish them from their stars.

What prevents the planets in our solar system from floating away?

The gravity of the Sun keeps the planets in their orbits. They stay in their orbits because there is no other force in the Solar System which can stop them.

How does the Doppler shift allow us to measure distance?

The redshift phenomenon is a manifestation of the Doppler effect – the faster the motion, the larger the shift of the frequency. Therefore, the larger the redshift, the greater the distance to the observed galaxy. The exact relation between the redshift and distance follows from the cosmological model of the universe.

What are two ways methods that scientists can use to discover planets orbiting other stars explain how they are used?

Bottom line: The most popular methods of discovering exoplanets are the transit method and the wobble method, also know as radial velocity. A few exoplanets have been discovered by direct imaging and microlensing.

How do planets float in space without gravity?

There are two reasons that objects seem to be floating without gravity in space when they are really falling. Each galaxy is held together by strong gravitational forces. The second reason that gravity is not so obvious in space is because objects tend to orbit planets instead of hitting them.

How do the distances between the inner planets compare to the outer planets?

There is no difference between the distances of the orbits of the inner planets and the outer planets. The planets are all equally distanced from each other.

Why can’t we see planets through the light of stars?

The hotter the star, the brighter the light. Planets are not hot enough to produce light, so the only way we can observe them is if light from the Sun is reflected off them. The biggest ‘planet’ we get to see is the moon, and the only way we can see that is if the Sun shines on it.

Why can we see exoplanets thousands of light years away?

The reason why we can see exoplanets thousands of light years away but not a planet 200 AU away (about 30 light-hours) is because these planets are found using different techniques.

How far away are the planets we have detected?

We haven’t detected planets millions of light years away. Right now the most distant is less than 20,000 light years away. Even for the planets we have detected, they are for the most part not “seen” or imaged directly. Instead they are found by the effect they have on the parent star (usually gravitational wobble or transit detection).

How do we detect planets outside our Solar System?

Other detection techniques for planets outside our solar systems include: measuring the wobble of a star due to a planet’s gravity pulling on it. directly imaging the planet with a high-resolution telescope like the Hubble Space Telescope.