How do they measure distance in space ??

-

One night i was surfing on my mobile and i came to know that nearest galaxy to us is Andromeda Galaxy which is about 2.5 million light years away from us. After reading it i was amazed and one question pooped up in my mind that 
How do scientists measure distance between objects in space ??

 First of all let us understand that distance in space is measured with reference to light i.e. in light years. One light year is the distance which light travels in one year which is approx 10 trillion km (9,500,000,000,000 km) which is so huge.

1.How do we measure distance with light ??

We measure distance by using time taken by light to reach at an object and multiplied that time with speed of light.For example Suppose light takes 2 hours to reach from one object to another.
So the distance= speed*time
                        = 1,080,000,000km/hr * 2hr
                        = 2,160,000,000 km

2.But nearest galaxy is 2.3 million light years away, so do we need to wait 2.3 million years ??

This was confusing but then i found that there are other methods to measure distance with the help of light which is called trigonometric parallax.

 Trigonometric parallax  is pretty simple. In this we see  an object from two or more different positions  and then calculate the distance and to a surprise these stars are so far that we cannot measure their distance even after having two different telescope at opposite end of equators.

3.So how to measure the distance from two very far position ??

Scientists found interesting solution to this and they used the revolution path of earth around sun.

 They used to measure the 1st position of star at a moment and after 6 months when earth completes its half revolution then they measure the 2nd position and then calculate the final position.

4.But this method only works for the objects no more then a few thousand light years away, then how we discovered Andromeda galaxy ??

Beyond our galaxy the parallax is too small to detect with even our most sensitive instruments. So we need to use another method which is called Standard candles.
Standard candles are the objects whose intrinsic brightness or luminosity we know really well.
For example, if we know how bright your light bulb is and you walk away from it and the light which we will receive will decrease by square of distance. So by comparing the light that we receive by intrinsic light of object we can tell that how far the bulb is.
In space, our light bulb is a special type of star called CEPHEID VARIABLE.These are unstable, like continuously inflating and deflecting balloon. And because of this inflating and deflation causes their brightness to vary we can calculate their luminosity by measuring the period of this cycle.By comparing these lights we calculate the distance how far they are.


Unfortunately this method also have limitation.

We can only observe individual stars up to about 40 million light years away, after which they become too blurry to resolve.

 But lucky we have a special type 1A supernova.

Supernovae are the giant explosions, away in which stars dies. These explosions are so bright that they outshine the galaxies where they occur

With the help of these supernovae we can measure the distance over several billions of light years away.
From all this we learned new methods which are used to measure distances in space, which are:
1.Speed*time
2.Trigonometric parallax
3.Standard candles

For any query , suggestion or feedback you can comment below or reach me at:
Facebook    Instagram    Google+    Email

Comments

Post a Comment

Popular posts from this blog

Goosebumps:-Inherited but useless ??

-
Image
What if i throw chilling water on you or scare you will a big booom?? Your initial reaction will be a shock or after that you will yell at me.But why i am talking about this to you?? Thats because we are going to discuss about an ancient phenomenon which is inherited but has no use for us today.And that is Goosebumps. What are goosebumps ?? Let us get inside bathroom and gather some courage to take a bath.When you stand naked or after pouring cold water on your body, you will observe tiny pores rising up on your skin like our hairs on arms and legs will stand and cause uneven skin and thats what we call goosebumps . These are one of the inherited traits we got from our ancestors . And these are mostly useless now a days. We will know the reason further in the blog. When do Goosebumps occur?? There are mainly 3 reasons for goosebumps to occur: Reaction to cold Reaction to shock (fear) Reaction to music How do goosebumps occur ?? Goosebumps occur when w...
Read more

History of calender

-
Image
From years we humans are using calendars to determine the date or days. In fact our very first task after getting up from sleep is to look at calendar and plan accordingly. But you ever thought that from where these calendars are originated ??  Let us start with What is calendar?? A calendar is a system of organizing days for social, religious, commercial or administrative purpose.This is done by giving names to periods of time typically like day, weeks, months and years. The term calendar is taken from calendae, the term for first day of month in the roman calendar,related to the verb calare "to call out", referring to the "calling" of the new moon when it was first seen. Latin calendarium meant "account book, register" (as accounts were settled and debts were collected on the calends of each month). The Latin term was adopted in Old French as calendier and from there in Middle English as calender by the 13th century (the spelling calendar is ...
Read more

How our kitchen is shortening our lifespan by 10-15 years ??

-
Image
Do you want to live for 80-90 years ?? I wish i can and many of you will also.And if someone of you don't want to live long than you must rethink and rediscover your aim and ambition. So, its clear that we all want to live long but the thing really matters is that are we trying to do so ?? Some of you may say YES, you might be exercising to keep your body young and you must be doing it but you are doing so because you know that it is beneficial. You know that smoking and drinking is injurious to health and its best to avoid it. But what if i say that you are destroying your health by your choice. And that choice is of the types of cookware you use to cook your food.YES that's correct , by the choice of your cookware you can increase of decrease your lifespan. As when we cook some part of the utensil/cookware gets into our food and affects our health. Our choice decides our destiny... So let us understand this topic in some detail as it is going to add so...
Read more