Hubble's Law Distance Calculator

Hubble's Law Equation:

\[ d = \frac{v}{H_0} \]

Distance (d):

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1. What is Hubble's Law?

Hubble's Law describes the relationship between the recessional velocity of galaxies and their distance from Earth. It states that galaxies are moving away from us at speeds proportional to their distance, providing evidence for the expansion of the universe.

2. How Does the Calculator Work?

The calculator uses Hubble's Law equation:

\[ d = \frac{v}{H_0} \]

Where:

\( d \) — Distance in megaparsecs (Mpc)
\( v \) — Recessional velocity in kilometers per second (km/s)
\( H_0 \) — Hubble constant in km/s/Mpc

Explanation: The equation calculates the distance to astronomical objects based on their observed redshift and the current value of the Hubble constant.

3. Importance of Hubble's Law

Details: Hubble's Law is fundamental to modern cosmology. It provides the primary method for measuring distances to distant galaxies and supports the Big Bang theory of the universe's origin and expansion.

4. Using the Calculator

Tips: Enter recessional velocity in km/s and Hubble constant in km/s/Mpc. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the current accepted value of H₀?
A: The Hubble constant is approximately 70 km/s/Mpc, though precise measurements range from 67-74 km/s/Mpc depending on the measurement method.

Q2: How is recessional velocity measured?
A: Recessional velocity is determined by measuring the redshift of spectral lines from astronomical objects using spectroscopy.

Q3: What is a megaparsec (Mpc)?
A: One megaparsec equals approximately 3.26 million light-years or 3.086 × 10¹⁹ kilometers.

Q4: Does Hubble's Law work for all distances?
A: Hubble's Law works best for distances beyond our local group of galaxies. At very small distances, local gravitational effects can dominate over cosmic expansion.

Q5: What is the Hubble tension?
A: The Hubble tension refers to the discrepancy between measurements of H₀ from the early universe (cosmic microwave background) and measurements from the local universe (supernovae).