Solar Storms

21 04 2009

The sun is our constant companion; it supplies heat and light to us and keeps our small blue/green world from freezing. However, as serene as the sun seems on a lazy summers day, a close look at its surface tells a very different story. Read the rest of this entry »

The Sun – lifecycle

3 03 2009

Over the course of a human lifetime, the Sun is an unchanging, constant companion – bringer of light and heat and champion of the day. It is often tempting to believe that it will always be here and always has been here. The truth, however, is quite different.

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Comet Lulin

24 02 2009

A fairly bright comet is passing through the solar system right now: C/2007 N3 (Lulin), or just Comet Lulin to its friends. Over the next few days it’s passing very close to the position of Saturn in the sky, making it a very easy target to spot. Take a look at a map of Lulin’s position for tonight courtesy Jodrell Bank. Sky and Telescope also has PDF maps of the comet position for various dates.

Its position near Saturn in Leo means it’s up practically all night right now; it rises around sunset, so look East for it. With binoculars it should be pretty easy to find; its brightness is hovering just above naked-eye visibility, so it’ll be an obvious fuzzy ball near Saturn.

Spectacular Saturn Transit

19 02 2009

Something is about to happen on Saturn that’s so pretty, even Hubble will pause to take a look.

“On Feb. 24th, there’s going to be a quadruple transit of Saturn’s moons,” says Keith Noll of the Hubble Space Telescope Science Institute. “Titan, Mimas, Dione and Enceladus will pass directly in front of Saturn and we’ll see their silhouettes crossing Saturn’s cloudtops—all four at the same time.”

Hubble won’t be the only one looking. Amateur astronomers will be able to see it, too.

Transits like these are rare. “They only happen every 14 to 15 years when the orbits of Saturn’s moons are nearly edge-on to Earth,” says Noll. In 1995-96, the last time the geometry was right, Hubble photographed two (Titan and Tethys) and three (Mimas, Enceladus, Dione) moons transiting Saturn. This will be the first time the great telescope captures four.
The event begins on Tuesday morning, Feb. 24th at 10:54 UT when Titan’s circular shadow falls across Saturn’s cloudtops. About forty minutes later, the ruddy disk of Titan itself moves over the clouds.

“Titan is so big, you can see it just by looking through the eyepiece of a small telescope—no special camera is required,” says Go.

One by one, the smaller moons Mimas, Dione and Enceladus will follow Titan. At 14:24 UT, all four satellites and their shadows will simultaneously dot Saturn’s disk.

Titan transits Saturn on Feb. 8, 2009. (Christopher Go, the Philippines)
Titan transits Saturn on Feb. 8, 2009. (Christopher Go, the Philippines)

In Saturns Shadow

11 02 2009

After successfully observing Venus, the Moon and Saturn (with tiny Titan) last night, I thought it was apt to show you this impressive panorama of Saturn, taken by the Cassini probe, currently in orbit around the ringed planet. Read the rest of this entry »


27 01 2009

An eclipse (from the Greek ekleipô, “to vanish”) is an astronomical event that occurs when one celestial object moves into the shadow of another. The term is most often used to describe either a solar eclipse, when the Moon’s shadow crosses Earth’s surface, or a lunar eclipse, when the Moon moves into the shadow of Earth. However, it can also refer to such events beyond the Earth-Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its parent planet, or a moon passing into the shadow of another moon. An eclipse is a type of syzygy (a line up of astronomical bodies), as are transits and occultations. Eclipses are impossible on Mercury and Venus, which have no moons. Read the rest of this entry »

The Winter Solstice

19 12 2008

A solstice is an astronomical event that occurs twice a year, when the tilt of the Earth’s axis is pointed toward or away from the Sun, causing the Sun to reach its northernmost or southernmost extreme. The name is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still in declination; that is, its apparent movement north or south comes to a standstill. This years winter solstice happens on the 21st December at 12.04. Read the rest of this entry »