February 23, 2023: After sunset, three bright planets and a crescent moon are easily visible. The bright winter stars of Orion are in the southern sky after sunset.
By Jeffrey L Hunt
Chicago, IL: Sunrise, 6:35 a.m. CST; Sunset, 5:34 p.m. CST. Check local sources for sunrise and sunset times for your location. Times calculated from the US Naval Observatory mica Computer program.
Transit times of Jupiter’s Great Red Spot, when it is in the center of the planet in the Southern Hemisphere: 9:28 UT, 19.24 UT. Convert the time to your timezone. In the US, subtract five hours for EST, six hours for CST, and so on. Use the telescope to see the spot. times of Sky and telescope magazine.
This evening he goes outside at about an hour after sunset. The stars of the Orion region of the Milky Way are located in the southern sky. The main constellation is Orion. It is easily recognized by the belt’s three stars. Betelgeuse red — meaning “armpit” — is top left and Rigel bluish, knee, is at bottom right.
More than a century ago, Henry Norris Russell and Einar Hertzsprung, along with their observational groups, identified fundamental stellar properties. One such important factor is that temperature determines color. Contrary to the artist’s interpretation of the colour, bluish stars are much hotter than reddish ones. The colors are not as bright as rubies or sapphires. They are subtle and easily seen through binoculars.
Annie Jump Cannon classified more than 350,000 stars into groups by their spectra, when starlight was passed through a prism and broken up into its component colors along with regions of less light than the elements in the stars’ outer regions. The spectral class indicates the chemistry of the star and uses the letters O, B, A, F, G, K and M, from blue to red. (O-type stars are the hottest and appear bluish, while M-type stars are the “coolest” and are reddish.)
Furthermore, Russell and Herzsprung independently plotted the stellar characteristics on a system known today as the HR chart. The x and y axes are marked with interchangeable terms. Absolute luminosity and volume are shown on the y-axis, while color, temperature, wavelength, or spectrum class can be displayed on the x-axis.
The absolute magnitude is used to compare the intrinsic stellar brightness. It is the brightness of the star if it is 10 parsecs or 32.6 light-years away. The magnitude system is a numerical classification of a star’s brightness. Lower numbers are brighter. At 10 parsecs, our sun has a rating of 4.8, invisible from most city and suburban backyards. By comparison, if Betelgeuse were at that distance, it might appear five times brighter than Venus in the night sky.
When the characteristics of the Sun are plotted on the graph, it is not as bright as the named stars in the sky, but much brighter than most of the faint stars close to our solar system. Astronomers sometimes refer to our central star as a “typical star” or “garden variety star,” because many other stars are similar to it. It looks average compared to other stars.
Use binoculars to view the Hertzsprung-Russell constellation of winter stars. Some optical aids amplify the star’s brightness in addition to its subtle colour. Here’s my round-up of the winter star sampler.
- spectral category a: Alnitac – the eastern star in Orion’s belt, Zeta Orionis (ζ Ori, m = 1.7), 815 light-years (Li) away;
- B: Riegel, Beta Oriones (β Ori, m = 0.2), 860 ly
- a: Sirius, Alpha Canis Majoris, (α CMa, m = −1.5), 9 ly
- F: Procyon, Alpha Canis Minoris (α CMi, m = 0.4), 11 ly
- g: Capella, Alpha Aurigae (α Aur, m = 0.1), 40 li
- K: Aldebaran, Alpha Tauri (α Tau, m = 0.8), 70 ly
- M: Betelgeuse, Alpha Orionis (α Ori, m = 0.4), 500 lei
Here are the forecasts for today’s planet:
Two morning planets immersed in the bright morning twilight. Mercury heads into its superior conjunction on March 17thy Then the best evening look of the year during the month of April. It rises about 30 minutes before the sun.
Saturn climbs into the morning sky after solar conjunction a week ago. It rises less than 10 minutes before dawn.
This evening Venus, Jupiter and the crescent moon, 18% illuminated, are in the west-southwest after sunset. Bright Venus lies roughly 20 degrees above the horizon, with Jupiter 6.2 degrees to its upper left.
The Crescent Moon, approximately 40 degrees above the horizon, about 15 degrees to the upper left of Jupiter. It shows the brilliance of the Earth in the night part. This effect reflects sunlight off Earth’s oceans, clouds, and land.
As the sky darkens, Mars rises in the south above the bright stars in the Orion region of the galaxy.
The red planet is moving east in front of Taurus. This evening passes between Elnath and Epsilon Tauri (ε Tau), in the “V” of Taurus, opposite Aldebaran. Elnath and Epsilon are too far apart to fit into the same binocular field of view, but they use it to define the star field.
Mars is 10.6° to the upper left of Aldebaran and 6.4° to the lower right of Ennath.
Over the next few weeks, watch every clear night as Mars approaches Taurus’ horns.
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