Describe one method by which the distance to stars from Earth is measured, and one modern improvement to this method which increases its accuracy.

One such method is Stellar parallax. When observing stars in the night sky, stars which are further away from Earth appear to 'move' less across the sky as the earth rotates. Using this, stellar parallax works by observing the position of the target star (the one you are calculating the distance of) relative to a star (or stars) 'behind' it. After 6 months, one half-orbit around the Sun, observe the target star's position relative to these distant stars again and measure the angle subtended by Earth to this star. This angle should be in arc seconds. The distance of the target star is given, in parsecs, by d=1/p. A recent improvement of this method is the ability to position telescopes in Earth's orbit (such as the Hubble Space Telescope), which removes any adverse effects of the Earth's atmosphere.