Physics

Ladd Skies Weekly

Ladd Skies Weekly, December 23 - 29, 2025

The beautiful winter constellations are just waiting for you to venture outside and enjoy.

Mercury is still in our morning sky, but it is quickly moving toward our Sun.  Venus already has moved too close to the Sun to be observed, but it will become part of our evening sky early next year.  

Have you noticed that Saturn is almost due south at sunset, making it very easy to observe. It is with us until just a bit after 11:00 P.M.  Jupiter, however, is visible all night, and can be seen with no trouble, as it is the brightest celestial object; It is still within the constellation Gemini, the Twins.  Again this week, there is a lot of activity for those who would like to follow the motions of Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto.  Please check an almanac for this.  Mars, though, is in the glare of the Sun, totally gone from our view in the evening.

The waxing crescent Moon is near Saturn on the 26th.  The next day it will become first quarter.   

If you’re still hoping to see the star T in Corona Borealis become as bright as that of our North Star, Polaris, it is rising this week about 1:45 A.M.

We’ve already introduced the ruddy eye of Taurus, the Bull, the star Aldebaran, and noted that it wasn’t as far away as the rest of the animal’s face.  You might notice the “V” of the face, and other stars near it.  These make up the other open star cluster in Taurus, called the Hyades.  It is actually a roughly spherical group of hundreds of stars, thought to be around 625 million years old.  It also is the closest of all open clusters, just 153 light years from us.

Last time, we mentioned the Apollo 8 astronauts, Frank Borman, Jim Lovell and William Anders, as the first astronauts to travel to the Moon and venture around it.  This was not an easy

concept, as they would have to be away from radio contact during that time, the first of any mission.  As they returned from the Moon’s far side on December 24, 1968, they took note of the seriousness of their task, plus the time of year, and proceeded to read from the book of Genesis, followed by a wish for a blessed holiday.

How many of us remember the “Comet of the Century,” Comet Kohoutek, that was to blaze through the sky like no other had ever done?  First discovered by Dr. Lubos Kohoutek in March, 1973, while he was studying asteroids, he discovered a comet about the distance to the planet Jupiter, yet it seemed almost too bright for one so far from the Sun.  He believed it would continue to brighten to the point that it would become the brightest comet ever observed.  However, that didn’t happen: The comet was barely visible to the naked eye, becoming 50 to 100 times dimmer than expected.  When it approached perihelion - closest approach to the Sun - on December 28, it did brighten a bit, but still never made the historic brilliance first expected.  

Although meteorites are mainly the result of space material striking our planet, occasionally we discover a rock from another source.  Such was the case on December 27, 1984, when a 4-pound rock was discovered by a meteorite-hunting party in Antarctica.  Upon examination, it was determined to have come from our neighboring planet Mars, and under microscopic observation, it was found to have what at first believed could have been fossilized material.  Now referred to as ALH 84001, we know that what was thought to be an organic visitor from Mars is now just a part of the rock’s composition.

I’m sure many readers lost sleep on December 25th, 2021, not waiting for Santa Claus, but watching with bated breath for the launch of the James Webb Space Telescope from Guiana Space Center on an Ariane rocket.  Aimed for one of the Lagrange points, L2, located about a million miles from Earth, it spent several months before arriving at this intended position, where it has proven incredible in the amount of information sent back to us.  The largest telescope in space, it is not designed for visible light observations, but to perform infrared astronomy instead.  Instead of being made up of just one mirror, it has 18 separate gold-coated beryllium hexagonal mirrors, which equate to a surface 21 feet across.  It was designed to be functional for at least 10 years.

All of us at Ladd wish you the best holiday season ever, and we’ll be with you again in the New Year.

Francine Jackson,

Staff Astronomer

Ladd Observatory