Difference Between Absolute and Apparent Magnitude (With Table)

In this cosmos, there are an infinite amount of stars to be discovered. When we look up at a clear night sky, the entire expanse is illuminated by the stars, which appear as tiny bright colour spots in the sky. Some look to be brilliant, while others seem to be dark. Numerous variables may be at play in the fluctuation of luminance magnitude.

For example, the distance between the sun and the Earth or the energy level required to emit the electromagnetic wave (light) could determine. Hipparchus (a Turkish astronomer) was the first to envision a scale for standardizing the importance of a star thousands of years before the invention of the modern scale.

It later refined the previous scale used by Hipparchus to determine the magnitude of the luminosity of celestial bodies into two standards that were later derived from the earlier scale. The absolute magnitude and the apparent magnitude are the two standards that are now in use. Using absolute magnitude, we can determine the brightness of any celestial body when viewing it from a constant distance of ten parsecs away (one parsec equals 3.25 light-years).

Absolute vs Apparent Magnitude

The main difference between absolute magnitude and apparent magnitude is that absolute magnitude does not consider the size of the celestial body or the location from which it is observed. The apparent magnitude of any astronomical object determines the degree of brightness when seen from a certain point of reference. The absolute magnitude of a star measures the star’s intensity solely at a set distance from the observer.

Absolute magnitude is a measurement of a celestial body’s inherent brightness, measured in magnitude units (star). When seen from Earth, the apparent magnitude of any celestial body provides us with a vivid image of the object’s intensity. The evident magnitude scale produced by Hipparchus has evolved from an earlier version of the magnitude scale that he developed.

The apparent magnitude of any celestial body from the point of reference provides us with a clear image of the intensity of that cosmic entity with the parameters listed above.

Comparison Table Between Absolute and Apparent Magnitude

Parameter of ComparisonAbsolute MagnitudeApparent Magnitude
MeaningIt provides the magnitude of the brightness of a celestial body when observed from a certain distance in the night sky.This parameter indicates the brightness of a celestial body about the observer’s location (The Earth).
Scale usedThe scale is inverse logarithmic.The scale is in reverse logarithmic notation.
SymbolMv is the symbol used to represent it.The sign mv denotes it in this case.
Factors on which it dependsThe energy emitted by a star or a celestial body in one second.The size of the celestial body, the quantity of energy emitted by the body, and the distance between the celestial body and the Earth are all factors to consider.
HighlightsThere is no consideration for energy wasted due to light being absorbed by cosmic dust when evaluating brightness.When calculating the brightness, it considers all of the variables, such as the amount of energy absorbed by the interstellar material.

What is Absolute Magnitude?

It is the brightness of a celestial body viewed from a fixed distance of 10 parsecs measured in absolute magnitude (equivalent to thirty times the distance traveled by light in a year). Absolute magnitude refers to the intensity of light emitted by celestial bodies, and this tells us that its absolute magnitude drops when an object’s brightness increases. It is represented by the symbol Mv.

The absolute magnitude of a quantity can be calculated using the formula below.

2.25log([d/10]2)

Where;

d is the parsec distance.

M is the apparent magnitude.

The bolometer is used to measure the absolute magnitude, and it is a gadget that measures electromagnetic radiation.

Absolute magnitude describes the object’s intrinsic brightness, and this system ignores the energy absorbed by matter in space while measuring it. Absolute magnitude depicts the celestial body’s actual luminosity.

What is Apparent Magnitude?

An object’s apparent magnitude measures how bright it seems from the observer’s point of view, such as the Earth. It accounts for all the possible obstacles and absorbers of light in its route.

The symbol for apparent magnitude is mv. A reverse logarithmic scale is used for apparent magnitude. The naked eye can view celestial objects with apparent magnitudes ranging from -1 to 6.5. The apparent magnitude can be used to calculate the absolute importance as well. The formula for determining the relationship between absolute magnitude (Mv) and apparent magnitude (mv) is below.

Mathematically speaking, the difference between Mv and Mv is five log10 (d)

Main Differences Between Absolute and Apparent Magnitude

  1. The absolute magnitude of a celestial body is a technique of determining the intrinsic brightness of that body. The apparent magnitude of a light source is defined as the magnitude of the intelligence about the distance between the point of observation and the light source.
  2. It is possible to express the absolute magnitude of a celestial body’s brightness at a distance of ten parsecs from it as the object’s apparent magnitude when measuring the luminosity of a celestial body. Earth is our starting point for discussing the obvious immensity of the universe.
  3. The absolute magnitude does not consider any factors that may hinder the path of light emitted by the object. It refers to the actual luminance of the celestial body observed. However, apparent magnitude is determined by considering all of the variables that could influence the intensity of the light detected from the body.
  4. Mv denotes the absolute magnitude, but the apparent magnitude is represented by mv. The apparent magnitude is indicated by mv.
  5. An apparent magnitude measurement system uses photometric equipment; an absolute magnitude measurement system uses bolometers.

Conclusion

Astronomers frequently utilize the absolute or apparent magnitudes to verify the luminous intensity of a celestial object. It is possible to determine the actual value of a body by using absolute magnitude, and it is possible to decide on a star’s brightness based on its apparent magnitude.

References

  1. https://www.aanda.org/articles/aa/abs/2001/08/aa1919/aa1919.html
  2. https://adsabs.harvard.edu/pdf/2006JAHH….9..173H