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Introduction
3. The table star
Resolve tasks and learn about the cosmos

Instruction

Next we'll look at the other table, star. This table stores details about the stars in a given constellation.

First, let's learn some basic star facts.

A light-year is an astronomical measure describing the distance traveled by light in one Julian year (365.25 days). (Remember that light travels at about 300,000 \frac{km}{s}.) The distance covered in one light-year is about 9.46 trillion (9.46 \cdot 10^{12}) kilometers or 5.88 trillion (5.88 \cdot 10^{12}) miles. In this table, the distance column uses the ly unit (1 ly is 1 light-year).

In the observation of stars, we use also the apparent (visual) and absolute magnitudes:

  • The apparent magnitude (denoted by the symbol m) measures a star's brightness as seen from the Earth. The brighter an object is, the lower its magnitude. Apparent magnitude depends on the star's luminosity and its distance from Earth.
  • The absolute magnitude (denoted by the symbol M) measures how bright a star would be if it were observed from a distance of 10 parsecs. (The parsec (pc) is a unit of length used in astronomy. One parsec is about 3.26 light-years).

Each star also has mass, which is described by units of solar mass (M☉); one unit of solar mass equals the mass of the Sun.

Exercise

Select all data from the table star. It contains these columns:

  • id – The unique internal ID of that star.
  • name – The official name of that star.
  • constellation_id – The constellation to which that star belongs.
  • apparent_magnitude – The star's apparent magnitude.
  • absolute_magnitude – The star's absolute magnitude.
  • distance – The star's distance from our Sun, in light-years.
  • mass – The mass of that star.
  • temperature – The star's temperature, in Kelvin (K).