Home > Ephemeris Program, Exoplanets > Ephemeris: 08/03/2023 – What is a rogue planet?

Ephemeris: 08/03/2023 – What is a rogue planet?

August 3, 2023

This is Bob Moler with Ephemeris for Thursday, August 3rd. Today the Sun will be up for 14 hours and 35 minutes, setting at 9:06, and it will rise tomorrow at 6:32. The Moon, 2 days past full, will rise at 10:40 this evening.

Did you ever hear of something called a rogue planet? A rogue planet is an exoplanet without a star, wandering through interstellar space. A planet could be ejected from its planetary system through interaction with another planet, or maybe it’s in a multiple star system and usually the body with the lease mass loses and can be ejected from the system. Another way to create a rogue planet is to have a planet being created like a star but without enough mass to build it up and be left with too little mass to ignite the hydrogen within its core to create helium and thus begin to shine. Rogue planets are detectable by gravitational microlensing, causing a background star inline with the rogue planet and the Earth to briefly brighten. Rogue planets can be detected and studied because they are relatively warmer than the 3
Kelvin Cosmic Microwave Background. The James Webb Space Telescope is an ideal tool to study them. There may be more rogue planets than stars in the Milky Way.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.

This has been extensively modified from the presentation in the radio program.

Addendum

This artist’s conception illustrates a Jupiter-like planet alone in the dark of space, floating freely without a parent star. Astronomers recently uncovered evidence for 10 such lone worlds, thought to have been “booted,” or ejected, from developing solar systems. The planet survey, called the Microlensing Observations in Astrophysics (MOA), scanned the central bulge of our Milky Way galaxy from 2006 to 2007. It used a 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand, and a technique called gravitational microlensing. In this method, a planet-sized body is identified indirectly as it just happens to pass in front of a more distant star, causing the star to brighten. The effect is like a cosmic funhouse mirror, or magnifying lens light from the background star is warped and amplified, becoming brighter. Based on these results, astronomers estimate that free-floating worlds are more common than stars in our Milky Way galaxy, and perhaps other galaxies too. Credit: NASA/JPL via Wikipedia.
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