2022, October 3: Exoplanet, Planetary Platter

October 3, 2022: The Webb Space Telescope recorded the first image of a planet around another star.  Jupiter, Saturn, Mars, and Mercury are easy to spot during the night.

PODCAST FOR THIS ARTICLE

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:50 a.m. CDT; Sunset, 6:29 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

The first image of a planet around another star was made recently by the Webb Space Telescope.  Certainly, it’s not a portrait to hang on the wall.  It does not rival a photo of Saturn with its rings or the cratered moon.  The image is made of a few dots on the electronic detectors, along with some residual light from the electronics and telescope optics. Multiple infrared filters were used to capture the planet’s image.

The star graphic shows the star’s position.  A mask was used to block its brightness and any residual starlight was subtracted from the view.

Occulting a brighter object’s light to see a dimmer sight is frequently used in astronomy.  It is similar to putting up your hand to block the sun’s glare.

Before this first image, made by Webb’s infrared eye, there was indirect evidence of unseen objects revolving around nearby stars.  The technique was first used to find dimmer stellar companions. 

When the unseen object revolves around the main star, the main star’s light dims when the object passes between Earth and the star.  When a regular pattern was observed, the orbital period was determined.

The object’s distance away from the star and the speed at which it revolves indicates the value of the revolving mass. This planet is about 10 times larger than Jupiter.

The planet revolves around a star catalogued as HIP 65426, a dim star – beyond the limit of human eyesight – in the constellation Centaurus.  (The European space agency’s Hipparchos satellite cataloged the positions of 2.5 million stars. Hence the HIP number.) The planet’s name is made by adding the letter “b” to the star’s catalog number HIP  65426 b. For our southern hemisphere readers, it is 4.0° south of the bright star cluster NGC 5139 – also known as Omega Centauri – and in the same binocular field of view.  From the Florida Keys, the star is about 15° up in the south on spring evenings.

Here is today’s planet summary:

Morning Sky

SUMMARY OF PLANETS IN 2022 MORNING SKY

MARS OPPOSITION 2022 SUMMARY

Mars continues its eastward march in Taurus, approaching the Bull’s horns.  Find it high in the southwestern sky an hour before sunrise.

Jupiter is very low in the west at this hour.

Mercury is beginning its best morning exhibition of the year in the east before sunrise.  Forty-five minutes before daybreak, it is over 5° above the horizon, below Leo.

While not impossible to see, Venus is a challenging view.  It rises 27 minutes before sunup and 10 minutes before the sun appears, it is very low in the east.  A binocular is needed to make the initial observation.

Evening Sky

After sunset, Jupiter, Saturn, and the moon are lined up from east to south.  The waxing moon, this evening distinctly gibbous and 62% illuminated, is over 20° up in the south an hour after sunset.  Bright Jupiter is over 10° above the east-southeast horizon. Saturn, dimmer than Jupiter, is about two-thirds of the way from the Jovian Giant to the moon and 25° above the south-southeast horizon.

Before midnight, three bright planets are strung across the sky.  Bright Jupiter is in the south.  Mars is low in the east-northeast, while Saturn is in the southwest.

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