Everything you always wanted to know about astronomy

The Hubble Space Telescope was sent up to be an orbital observatory, much better than any Earthbound obseratory, several years ago. The idea was that it would 'see' more clearly above the dirty atmosphere. Since there would be no dirt nor gases (that would disperse the incoming light into several directions) to partially block the light, the Hubble would be able to 'see' further away, to resolve into the smaller distances, and to bring us views that we have never seen before. After a few corrections to some major setbacks (the mirror had been ground to the wrong curvature and could not focus an image, the gas used to reposition the satellite was running low, etc.), the telescope was good for the next 5 to 10 years. That was about 15 years ago. Now there are some big plans for the ailing telescope: while in orbit, astronauts will fit it with 2 new instruments which will dissect the ultraviolet light and produce more sensitivity than before. While they're there, the Shuttle astronauts will replace circuit boards, guidance sensors, gyroscopes, and batteries. They'll add insulative blankets and raise the decreasing orbit to a higher one. This will probably allow the telescope to last another 10 years, when this maintenance is due again. Go to www.skyandtelescope.com/newsblog for astonomy news as it breaks. This site will help to keep you posted.

Mars and Saturn will be blazing in the early night sky; Saturn much brighter than Mars. If you wait until the last couple weeks of April, Mercury will show up very close to the Sun. When the Sun rises, it'll be followed by Jupiter and Venus. But Venus will be so close to the Sun that the bright light from the Sun will cause it to be obscured from our view.

Mercury, behind the Sun in its orbit, will not be visible for the first couple weeks of the month. The Mariner 10 probe, a NASA rebote satellite sent up in 1974, took the first close-up photographs of its surface. In 2009, the Messenger probe will get to within 126 miles of its surface (about 500 miles closer) and then go into orbit around it. Messenger will carry instuments to find out about the planet's magnetic field, the thin atmosphere, and the presence of ice under the poles. It will also radio back evidence of its iron-rich surface and its high density. It's been 33 years since we've sent a satellite to Mercury! During the last weeks of April you will find Mercury in the West, near the horizon, immediately after the Sun sets.

Mars, like last month, is high in the West at sunset. It sets about midnight. Since it is getting slightly further away, it gets slightly smaller during April, but it gets a greater phase. Because of this, the planet may seem to get slightly brighter. Use binoculars to see the deep orange of the planet.

High in the South at sunset, Saturn comes into view as soon as the sky gets dark enough for the bright 'stars' to become visible. By the end of April, the rings are tilted more than they have been in months. They won't be tilted this much again until 2010. Be sure that you view this. You will remember this beatiful sight for years.

Jupiter is best observed early in the morning in the Southeast. Its moons will disappear (eclipse) behind the planet due to the plain of their orbits. This is a sight that you don't want to miss. The moons move fast enough in their orbits so you can watch this happen in one night. In July, Jupiter will reach opposition and become invisible to our observations.

Venus is entering opposition (in case you've forgotten, it'll be behind the Sun) this month, and will be impossible to see until July or August. At that time it'll become visible, very low at sunset.

The moon is near Venus on the 4th. The New Moon occurs on the 5th. On the 8th, the moon is very close to the Pleiades (7 Sisters). On the 11th, the moon passes close to Mars. On the 14th, the moon is to the right of Saturn. On the 20th, we are treated to a Full Moon. On the 27th, the moon is just below Jupiter at dawn. Happy viewing.

Bruce Dennis is a retired science teacher from Haverling high school.