# I was learning about the Parallax method of distance measurement and thought of something.

The parallax method is a geometrical method, normally used by astronomers to detect the distance to a star, or any celestial body from Earth. It is commonly known as **Trigonometric Parallax** or **Stellar Parallax**, which uses the apparent shift in the background against which the star is seen.

To measure such shifts, it uses two angles, each of which is formed by viewing the star from two different points on the Earth’s orbit.

It is measured by simply taking the two angles and the distance between the two points on the orbit, i.e. 2 AUs, and using basic trigonometric functions to determine the distance.

Due to the huge difference in the distance to the actual star and the two points in the orbit, the value of the angle computed, i.e. theta, measured in degrees, is so small that it is almost negligible. To combat this problem, physicists have come up with the idea of dividing each of those degrees into smaller parts known as **Arcminutes****. **An Arcminute is defined to be one-sixtieth of a degree.

An **Arcsecond** is again a further break-up of an Arcminute, where one 1 arcsecond equals one-sixtieth of an Arcminute and one three thousand six hundredths of a degree.

Normally, when the distance to local stars is measured, the angles are computed in Arcseconds, to get a more accurate value.

The “distant stars” are used as the background, against which the star in question is used under parallax. The value of ‘p’ is the angle that is measured in arcseconds. Then using basic geometric properties like similarity of triangles, and the trigonometric value of Tangent, the distance to the star is determined.

But one shortcoming of this method is that the value of ‘p’ is so small, even in arcseconds, that it makes it hard to accurately measure the distance of distant objects. This problem arises due to the limited distance between the two different points in the Earth’s orbit.

So what if we are able to send a satellite across the solar system, to the maximum distance possible where we can still receive data and images fast enough, maybe in a few light days or weeks, and increase the distance of the base, thus increasing the value of the angle? This would also ensure that the apparent background of the star is also different than when viewed from just 2AUs away.

Practically, it does seem like it requires a lot of time, cost and energy to have a satellite just do that. So adding such a function to an already existing satellite mission, like the Voyager or the New Horizon that is located about 30 AUs away, would ensure an energy-saving space mission and an efficient way to determine the distance to deep-space objects.