Question

How big is the universe in AU?

Answer 1

Hint: The radius of the observable universe is therefore estimated to be about 46.5 billion light-years and its diameter about 28.5 gigaparsecs (93 billion light-years, or 8.8×1026 metres or 2.89×1027 feet), which equals 880 yottametres.

Complete step by step answer:
The astronomical unit (symbol: au, or au or AU) is a unit of length, roughly the distance from Earth to the Sun and equal to about 150 million kilometres (93 million miles) or ~8 light minutes. The actual distance varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year.
The size of the universe depends a great deal on its shape. Scientists have predicted the possibility that the universe might be closed like a sphere, infinite and negatively curved like a saddle, or flat and infinite.
According to NASA, scientists know that the universe is flat with only about a 0.4 percent margin of error (as of 2013). And that could change our understanding of just how big the universe is.
Using Hubble constant, the observable universe is at least $ 13.8{\text{ }} \times {\text{ }}2{\text{ }} = {\text{ }}27.6 $ billion light years across, and in AU unit, this is $ 27.6{\text{ }} \times {\text{ }}62900 $ billion AU = $ 1.74 $ million billion AU.
Further research reports reach an estimated 93 billion light years and this is 93 X 62900 billion AU = 5.85 million billion AU.

Note:
Scientists measure the size of the universe in a myriad of different ways. They can measure the waves from the early universe, known as baryonic acoustic oscillations that fill the cosmic microwave background. They can also use standard candles, such as type 1A supernovae, to measure distances. However, these different methods of measuring distances can provide answers.