Mars Meets the King of the Beasts

I was up before dawn today hoping to find the returning comet 205P/Giacobini and a faint new supernova in the galaxy IC 1776 in Pisces. I was fortunate to see them both. But the morning held a pleasant surprise I hadn’t anticipated. Venus rose brilliantly in the east followed by the much dimmer planet Mars some 10° to its lower left. And there, not more than a couple degrees below Mars, shone Leo’s brightest star, Regulus. At first glance both appeared about equally bright, but looking closer, it was clear that Regulus, at magnitude +1.3, bested Mars by nearly half a magnitude. What was especially appealing was the color contrast between the two with Mars’ dusty, rusty surface so different from the pure white radiance of Regulus.

On Friday morning September 25, Mars and Regulus will be just 0.8 degrees apart in the eastern sky below brilliant Venus at dawn. They’ll be nearly as close Thursday morning. Source: Stellarium

While star and planet are both close enough to catch the eye, they’re headed for an excellent conjunction Thursday and Friday mornings, September 24 and 25. The actual time of closest approach, when star and planet will be separated by just 0.8°, occurs around 11 p.m. CDT — before Mars rises for skywatchers in the Americas and Canada, but about perfect for European and African observers.

Just the same, everyone around the planet will see them less than a degree apart low in the eastern sky about 90 minutes to an hour before sunrise on those dates. Joining the scene will be Venus, now spectacularly bright against the deep blue, early dawn, and Jupiter, bringing up the rear further lower down in Leo’s tail.

Regulus is a main sequence star like the Sun but hotter. It spins so fast that it’s stretched into an oblate spheroid 4.3 times the diameter of the Sun.

Regulus, Latin for “little king”, may have received that name because it’s the brightest star in the Leo the Lion, king of the beasts. The ancient Greeks knew it by the same name, Basiliscos, as did the Babylonians before them who called it Lugal (king). Regulus is the only 1st magnitude star to sit almost directly on the ecliptic, the path followed by the Moon, Sun and planets through the sky. That means it gets regular visitors. Mars this week; Venus and the crescent Moon both on October 8. Few bright stars are as welcoming of unannounced guests.

I encourage beginning and advanced astrophotographers alike to capture the Regulus-Mars conjunction using a tripod-mounted camera.  Just find an attractive setting and make a series of exposures at ISO 800 with a standard 35mm lens. Click here to find out when the Sun rises, so you’ll know what time to back up from to see the event. Now that fall brings much later sunrises, it’s not so hard anymore to catch dawn sky offerings.

It’s also a delight to see the Red Planet again, which will come to a close opposition in the constellation Scorpius next May. Let the fun begin!

Bob King

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. I also write a daily astronomy blog called Astro Bob. My new book, "Wonders of the Night Sky You Must See Before You Die", a bucket list of essential sky sights, will publish in April. It's currently available for pre-order at Amazon and BN.

Recent Posts

NASA Launches DART, to Learn how to Defend the Earth From a Future Asteroid Impact

NASA's Double Asteroid Redirection Test (DART) just launched and will intercept a Near-Earth Asteroid (NEA)…

9 hours ago

It’s Time to Stop Doing Anti-Satellite Tests

Earlier this month, the Russian military conducted an anti-satellite (ASAT) missile test, launching a PL19…

2 days ago

Stars Getting Kicked out of the Milky Way can Help us map its Dark Matter Halo

Hypervelocity stars may allow us to map dark matter as they leave the Milky Way.

2 days ago

A Machine-Learning Algorithm Just Found 301 Additional Planets in Kepler Data

Using a new type of deep-learning algorithm, a team of NASA scientists have detected 301…

2 days ago

Astronomers Find a Planet That Orbits its Star in Just 16 HOURS!

Mercury is the speed champion in our Solar System. It orbits the Sun every 88…

3 days ago

The Severe Pacific Northwest Flooding Seen From Space

The severe flooding that happened this month was captured by Earth Observation satellites, showing the…

3 days ago