H

• Born in USA.
• He was the first to recognize the importance of the magnetic fields of sunspots.
• He invented the spectoheliograph.
• He was responsible for having the largest reflector telescopes in the US set up.

Edmund Halley (1656-1742)

• Born in England.
• He drew the first good star map of the southern stars.
• He completed a study of the movements of the Moon.
• He probably is best known for his work on comets, one of which is named after him.

William Herschel (1738-1822)

• Born in Germany.
• He discovered the planet Uranus.
• He was the first to work out the shape of a galaxy.
• He established that double stars are binaries.
• He discovered star clusters and nebulae and made observations on the planets.

Ejmar Hertzsburg (1873-1967)

• Born in Denmark.
• He found that red stars are either giants or dwarves, but not in-between.
• He drew a diagram (H-R) according to the luminosity and colour of stars.
• He devised a method of estimating stellar distances by examination of the spectra of the stars.

Johannes Hevelius (1611-1687)

• Born in Poland.
• He built quadrants, sundials, and telescopes.
• He produced the best lunar map of his day.

Jeremiah Horrocks (1619-1642)

• Born in England.
• He correctly predicted that Mercury and Venus would transit across the face of the sun in 1631.

Edwin Powell Hubble (1889-1953)

• Born in USA.
• He proved that the starry nebulae are independent galaxies.
• He divided galaxies into classes according to their shapes.
• He found that there is a link between the distance of a galaxy and the speed in which it is moving away.

William Huggins (1824-1910)

• Born in England.
• With the aid of a spectroscope on his telescope, he found dark lines on the spectra of Betelgeuse and Aldebaran and other stars. Thus, he determined that Sirius is moving away by noting red-shifting.
• He showed that the nebulae are gaseous and that the planets shine by reflecting light from the Sun.
• He also obtained photographic stellar spectra.

Christiaan Huygens (1629-1695)

• Born in Holland.
• He discovered what the rings of Saturn are.
• He also discovered Titan, one of Saturn’s satellites.
• He made the first drawing of Mars that showed the surface detail.
• Numerous lenses and clocks were made by him.
• His main contribution to science was his belief that light is a wave motion.