DSST Astronomy (Part 11): Units of Measure

The current radius of the Sun. Used to express the size of stars. Approximately 695,500 kilometers or 432,160 miles (about 110 times the radius of the Earth). In scientific notation, 7x10^5 km

The distance from Earth to the Sun. Measures relatively short distances between points in space. Approximately 150 million kilometers or 93 million miles. In scientific notation, 1.5 x 10^15 km.

The distance light travels in a year. Measures vast distances between points in space. Approximately 10 trillion kilometers or 5.9 trillion miles. In scientific notation, 9.5 x 10^12.

The distance of the parallax of one second of arc. Measures vast distances between points in space. Equal to 3.26 ly. Approximately 30 trillion kilometers or 19.2 trillion miles. In scientific notation, 3.1×10^13 km.

The current mass of the Earth. Used to express masses of rocky planets. Approximately 6.0 sextillion metric tons. In scientific notation, 5.98 x 10^24 kg.

The current mass of the Sun. Used to express the mass of stars and galaxies. Approximately two nonillion kilograms (332,950 times the mass of the Earth). In scientific notation, 2 x 10^30 kg.

One giga (billion) years before present. Used to measure large units of time. In scientific notation, 10^9 yr.

The current luminosity of the Sun. Used to express the luminosities of stars in Watts. In scientific notation, 3.9 x 10^26 W.

Solar Radius (7x10^5 km)

Astronomical Units (1.5 x 10^15 km)

Light Year (9.5 x 10^12)

Parsec (3.1×10^13 km or 3.26 ly)

Earth Mass (5.98 x 10^24 kg)

Solar Mass (2 x 10^30 kg)

Gigayear (10^9 yr)

Solar Luminosity (3.9 x 10^26 W)