The Cancer constellation features two notable celestial objects: the ancient Beehive Cluster and the distant exoplanet 55 Cancri e.
The Beehive Cluster (M44)
The Beehive Cluster, also known by multiple names including Praesepe, Nubilum, M44, the Ghost, and Jishi qi, is a large open cluster of young stars located at the center of the Cancer constellation.
Remarkably, it is three times larger than the Moon in the sky. Under optimal sky conditions, it is visible to the unaided eye as a faint, cloudy patch and can be observed more clearly with binoculars or a wide-field telescope. To locate it, simply identify its position between the constellations of Gemini and Leo, using nearby stars such as Regulus in Leo, Pollux in Gemini, and Procyon in Canis Minor.
Exoplanet 55 Cancri e (Janssen)
55 Cancri e, officially named Janssen, is a 'super-Earth' exoplanet that orbits the larger star within the 55 Cancri binary system, situated approximately 41 light-years from Earth.
This remarkable planet boasts a mass eight times that of Earth and completes an orbit in an astonishing 18 hours, making its year one of the shortest known for any planet.
Janssen holds the distinction of being the first exoplanet for which atmospheric analysis was successfully conducted. Data gathered from the Hubble and Spitzer space telescopes confirmed that its atmosphere consists of helium and hydrogen, with traces of hydrogen cyanide. The planet's surface is believed to be scorching-hot rock.
Exoplanet Detection
The discovery of 55 Cancri e occurred in 2004 using the wobble method, a technique that detects the subtle gravitational tugs a planet exerts on its host star.
Later, in 2011, the transit method was employed to confirm its precise orbital period. This method involves observing a planet as it passes directly in front of its star, causing a slight dip in the star's brightness.