Constellations & Mercury Study Guide
■ Mercury – The Swift Planet
• Closest planet to the Sun and the smallest in the Solar System.
• Orbits the Sun in 88 Earth days; rotates once every 59 Earth days.
• One Mercury day (sunrise to sunrise) = 176 Earth days.
• Surface covered with craters; largest basin: Caloris Planitia.
• Extreme temperatures: 430°C daytime, –180°C nighttime.
• Very thin atmosphere (exosphere), weak magnetic field, no moons or rings.
• Missions: NASA MESSENGER (2011–2015), ESA BepiColombo (in progress).
■ [Mercury Orbit Diagram Placeholder]
■ Earth’s Revolution
• Earth orbits the Sun once every 365¼ days (leap year every 4 years).
• Orbit is elliptical (oval).
• Axis tilt: 23.5° — causes seasons.
• Different constellations appear in different seasons (Orion in winter, Scorpius in summer).
■ [Earth Orbit & Tilt Diagram Placeholder]
■ Constellations
Aquila
■ [Aquila Constellation Diagram Placeholder – Brightest Star: Altair]
• Altair – Brightest star; part of the Summer Triangle; summer sky.
Boötes
■ [Boötes Constellation Diagram Placeholder – Brightest Star: Arcturus]
• Arcturus – Orange giant, 25× Sun’s size; kite shape; 'Follow the arc to Arcturus.'
Canis Major
■ [Canis Major Constellation Diagram Placeholder – Brightest Star: Sirius]
• Sirius – Brightest star in the night sky; winter constellation near Orion.
Canis Minor
■ [Canis Minor Constellation Diagram Placeholder – Brightest Star: Procyon]
• Procyon – Smaller companion of Orion; near Gemini.
Cassiopeia
■ [Cassiopeia Constellation Diagram Placeholder – Brightest Star: Five-star 'W' shape;
circumpolar in the northern sky.]
• Five-star 'W' shape; circumpolar in the northern sky.
Cepheus
■ [Cepheus Constellation Diagram Placeholder – Brightest Star: Alderamin]
• Alderamin – House shape; includes Delta Cephei (variable star).
Cygnus
■ [Cygnus Constellation Diagram Placeholder – Brightest Star: Deneb]
• Deneb – Swan/Northern Cross; seen along the Milky Way in late summer.
Draco
■ [Draco Constellation Diagram Placeholder – Brightest Star: Eltanin]
• Eltanin – Long, winding dragon wrapping around the Little Dipper; visible all year.
All diagrams are placeholders for digital constellation outlines. Print and use for study or
labeling practice.