Teaching teenagers to curb their angry impulses is a challenge for every parent on the planet.

ECONOMIST: America��s blind spot

The conclusion: The tiny bright blob was an object still embedded in the disk of material around the parent star, suggesting a planet in the earliest stages of coming into being.

WSJ: Possible New Planet Spotted Under Formation

But if the planet's orbit is nearly edge-on, as viewed from Earth, then the planet will transit its parent star.

ECONOMIST: Transits of Venus

The most basic of the indexes rates a world's suitability for life based on its place within a habitable zone, which is calculated by a planet's distance from its parent star, the star's luminosity and temperature.

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One way they could have got there is if multiple planets have interacted in a gravitational "billiards game", in which one planet might have been flung in towards the parent star (sometimes to be swallowed whole), while another might have been thrown into an eccentric orbit, or perhaps even ejected from the system altogether.

BBC: Star 'eats' a planet

In their paper, the co-authors argue that gravitational tidal heating caused by the gravitational friction of an earth-like exo-moon on an eccentric orbit around a Jupiter-like planet lying at a Jupiter-like distance from its parent star, could, in fact, create habitable conditions.

FORBES: Earth-Like Exo-Moons Can Lurk Well Beyond Planetary Habitable Zones, Say Astronomers

Several monster planets have been discovered by looking for the wobbles in a star's spectrum caused by a planet's to-and-fro tugging of its parent.

ECONOMIST: Twinkle, twinkle, giant planet