Jared May: What's Up, February 15 - 22

This is the week of Valentine’s day and we stargazers may be getting some love from the skies. Some clear nights are forecast, possibly Tuesday as well as more over the weekend! The only downside to this is the temperature – once the sun has set the windchill will drop into the teens.

Sunset this week is right around 6:10 PM so have all your gear thermally equilibrated and be ready to stargaze no later than 7:10 PM.

During the clear nights this week, be on the lookout for an early-morning planetary trio, the full moon, the “first star” of the James Webb Space Telescope (JWST), and some stars of varying brightness.

If you are awake between 6:30 and 7:30 AM (whether you are getting ready for work or packing up from the previous night’s long astrophotography session), peer low in the eastern skies. You will notice three bright stars. Careful observation through a telescope or binoculars will reveal that these “stars” are actually Mercury, Venus, and Mars. A longer focal length telescope may show the polar ice caps on Mars, but just a set of binoculars will let the Red Planet’s color really stand out. This Wednesday, February 16, Mercury will be at its greatest western elongation. This is a fancy way of saying that Mercury will appear to be at its furthest point from the sun in our sky. Unfortunately, Mercury is very small and will not look too special with either telescope or binoculars.

Mercury, Venus and Mars on the morning of February 16.

Also on Wednesday, February 16, is the full moon. This means that most faint stars and deep-sky objects will be hidden by the moon’s glow. But a full moon provides an excellent time to use binoculars to view the total nearside of the lunar surface. Craters and ancient lava seas provide dark, contrasty, and colorful sights. If you have a telephoto lens and a DSLR, try taking a photo of the moon that is properly exposed (with these approximate settings: ISO 200, aperture f/4, shutter speed 1/500). Next, edit the photo by bringing down the highlights and boosting the saturation gradually. This will result in a true-color image of the moon. There will be more blues and yellows than what you probably expect to see.

The full moon washes out the stars, but is a worthwhile target for observation itself.

The JWST has been in space since Christmas morning of 2021, almost two whole months, and we just got the first images from this multi-billion-dollar space telescope! As part of its optics calibration process, the JWST took an image of star HD84406. With the help of binoculars or a telescope, you too can find this star. It is located right off the “bucket” of the Big Dipper. The JWST took a single photo that has 18 separate instances of this star due to each of its 18 mirrors acting as independent telescopes. Over the next few weeks, the mirrors will be carefully aligned so that we see just a single sharp HD84406 star instead of 18.

How to find the star that the JWST is using for its calibration. You’ll need binoculars to bring it into view, as it is just out of reach of the unaided eye.

When you look into the night sky you will see a wide variety of star brightness (many are too faint for the human eye to see) – every wonder why all stars aren’t the same? One obvious answer is that some stars are simply closer to earth than others, causing them to appear brighter than others (called “apparent magnitude”). A not-so-obvious answer is that there is a whole spectrum of types of stars, each with their own size, brightness, color, and age. The Hertzsprung-Russell (HR) diagram plots star brightness as a function of temperature. The sun is pretty average and sits near the middle of the largest collection of them on the H-R diagram, and hence is called a “main-sequence star”. Try spotting bright and dim stars and noting their color then compare with the HR diagram.

[Image from : https://astronomy.swin.edu.au/cosmos/h/hertzsprung-russell+diagram]

The Hertzsprung-Russell diagram is, perhaps, the most useful graph in Astronomy.

Feel the cold-hearted love this week of some clear skies both early in the week and late in the week accompanied by extremely frigid temperatures. Break out your telescope and your binoculars to stare up into the never-ending cosmos from the comfort of your own backyard. Enjoying desolate nights under the stars and darkness of night almost makes one feel like they are in space among the stars, nebulae, and galaxies. Try spotting some early-morning planets, the full moon and its true colors, the “JWST star”, and some bright and dim stars on the HR diagram.

Clear Skies!