Category: Astronomy

Exploring the cosmos

Apehelion

Today the Earth is furthest from the Sun, a point called apehelion. We will be about 152,096,000km (94,508,000miles) from the Sun. Compare this to the 147,099,000km (91,403,000miles) we were be at perihelion on January 1st, a difference of about 4,996,000km (3,104,000miles) occurring throughout one orbit.

It may seem odd that we are actually at the furthest for the middle of northern summer, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.

2013 Solstices and Equinoxes
  UT HST
Perihelion Jan 2 00:59UT Jan 1 14:59HST
Spring Equinox Mar 20 11:02UT Mar 20 01:02HST
Summer Solstice Jun 21 05:04UT Jun 20 19:04HST
Apehelion Jul 5 18:59UT Jul 5 08:59HST
Fall Equinox Sep 22 20:44UT Sep 22 10:44HST
Winter Solstice Dec 21 17:11UT Dec 21 07:11HST
 
Source: NASA Sky Calendar

 

The Moon, Mars and Jupiter

Tomorow morning, July 6th, will see a nice 5-7° triangle made up of a slim crescent Moon, Mars and Jupiter. Look for the trio to start rising about 04:30 HST with Mars rising first, followed by a 2.5% illuminated Moon. Last up will be Jupiter, rising about 04:55 HST. The Sun will not rise until 05:48 giving plenty of time to enjoy this conjunction.

Jupiter Appears in the Dawn

This week will see the reappearance of Jupiter in the dawn sky. This morning the planet will be 10° above the rising Sun, climbing quickly higher each morning. Look for a bright, -2 magnitude object directly above the bright glow of dawn.

Over the next couple weeks there will be a nice series of conjunctions between Jupiter, Mars, Mercury and the Moon.