Have you ever wondered how we measure the size of stars and planets from so far away?
Well, I have, and I will answer this question listing the five most common ways NASA measures stars within the reach of our telescopes.
Angular Diameter:
Firstly, we can measure planets within close proximity, by using a telescope and finding its angular diameter. The angular diameter of a circle is a plane that is perpendicular to the displacement vector between the point of view and the center of the circle that can be calculated using the equation Angular Diameter = 206265 X.
Occultation:
Another way is specifically for stars, by letting an asteroid block a star/sun, we can measure the amount of
time it blocks the star/sun, and how fast the asteroid travels, we call this occultation. If you know both of these factors you can make a rough estimate of the size of the star, by using mirrors to measure heat, and telescopes high powered telescopes you can find the size of stars. After using all this information, you can use trigonometry to find the diameter, then the circumference and finally the size of the star.
Parallax:
The third way to measure star and planets is by using the parallax method. The parallax method uses two opposite points of
view of the sun which takes a lot of time as we need to wait for earth to orbit to the opposite side of the sun. The parallax method works by using the length of the sun to the earth and creating a right triangle from two opposite views of the sun creating two right triangles. After creating two right triangle you can create more right triangles and using trigonometry until you find the star you would like to measure.
Cepheid’s:
The fourth way to measure stars is to measure the light from the star and how long it takes for the light to travel. Astronomers can predict the absolute magnitude of any given Cepheid by measuring the time it takes to rhythmically change its brightness. But first we have to know what the inverse square law is, the inverse square law is that the intensity₁ divided by intensity₂ muse equal distance2/2 divided by distance 2/1. Now by observing the apparent luminosity (light from an object from space), dimmed by the inverse square law of light traveling across the vast reaches of space, and comparing this with the predicted luminosity, astronomers can calculate the distance to that star.
The Kepler telescope / models based off of it:
And finally, the Kepler telescope, the Kepler telescope is quite simple it is a telescope that uses other measuring methods,
the Kepler standing at exactly 1-meter was named after an astronomer from the 17th century, Johannes Kepler, it is a telescope that floats in space and can look at specific spots in space for a long period of time. An advantage to using the Kepler telescope is its wide field of view and its ability to have great magnification while staying steady. Some serious drawbacks from using the Kepler telescope is the price to operate it, and repairs as it sat in space independently, and if damaged it was difficult to be brought back to earth. And on n October 30th, 2018, the Kepler telescope would run out of fuel, after observing half a million stars it would be retired by NASA, 587 lightyears from earth.
So how can we use this technology in other ways?
Well to start off, we use one of the most used type of math used by astronomers, Trigonometry, which we use commonly while building structures which we learn in high school. Another technological advancement is Kepler telescope, which can be used in many other ways such as studying wild life, and the more we can improve the telescope we can discover more planets and stars. Overall there is so much to discover and learn about our universe, and technology is only making it easier for us scratch the surface.
Work Cited
Alastair Gunn “How do astronomer measure the size of planets” Science Focus, date published unavailable
https://www.sciencefocus.com/space/how-do-astronomers-measure-the-size-of-planets/.Date accessed: 11 may, 2022
Phil Plait “How can we measure the a stars size” 16 April, 2019
https://www.syfy.com/syfy-wire/how-can-you-measure-a-stars-size-wait-for-an-asteroid-to-block-it. Date accessed: 12 may 2022
Jim Lucas & Tereza Pultarova “What is a Parallax” 11 January 2022
https://www.space.com/30417-parallax.html.Date accessed: 12 may,2022
Richard lynch “ how do astronomers use cepheids variables to measure distance” 24 august, 2015
https://astronomy.com/magazine/ask-astro/2015/08/astronomical-distances. Date accessed: 12 may, 2022
Laurel Kornfeld “ scientists use Kepler telescopes to study planets” 2 April, 2018