Some daily events in the changing sky for July 10 – 18.
Friday, July 10
Saturday, July 11
Now that we're far into summer, the Summer Triangle is very high in the east after dark, with the Moon-washed Milky Way running horizontally through it. Bright Vega is the Summer Triangle's highest corner. Lower left of Vega, by two or three fist-widths at arm's length, is Deneb. Farther to the lower right of Vega shines the triangle's third corner, Altair.
Sunday, July 12
Monday, July 13
Tuesday, July 14
Wednesday, July 15
Thursday, July 16
40th anniversary website.
Friday, July 17
Saturday, July 18
Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts; the standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.
Can a computerized telescope take their place? I don't think so — not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically: accurate and wobble-free. As Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand and a curious mind." Without these, "the sky never becomes a friendly place."
More beginners' tips: "How to Start Right in Astronomy"
This Week's Planet Roundup
Mercury is hidden in conjunction with the Sun.
Venus and Mars (magnitudes –4.2 and +1.1, respectively) are due east during dawn. Venus is a dazzler; Mars, to Venus's upper right, is 130 times fainter. They're moving farther apart: from 7° to 10° separation this week. Twinkly Aldebaran, similar to Mars in both brightness and color, is below Venus early in the week, and to Venus's right late in the week. Look above or upper left of Mars for the Pleiades.
Four reasons combine to create the great brightness disparity between Venus and Mars. Mars is farther from the Sun so it's illuminated less brightly; Mars is a smaller planet; its surface is darker and less reflective than Venus's white clouds; and Mars is currently farther from Earth.
In a telescope, gibbous Venus appears about 17 arcseconds in diameter; Mars is a tiny 5 arcseconds.
Jupiter (magnitude –2.7, in Capricornus) rises around 10 p.m. daylight saving time and shines highest in the south before dawn. In a telescope it's a big 47 arcseconds wide.
Saturn (magnitude +1.1, in Leo) is getting lower in the west after dusk. Look early! In a telescope Saturn's rings are narrowing, appearing only 3° from edge on. And see how they've dimmed! The rings will turn edge-on to the Sun and go black on August 10th. They'll turn edge-on to Earth on September 4th, but by then Saturn will be lost in the glow of sunset.
Uranus (magnitude 5.8, in Pisces), is high in the south-southeast before dawn.
Neptune (magnitude 7.8, in Capricornus) remains only about 3/4° from Jupiter, but it's 16,000 times fainter. See our finder charts for Uranus and Neptune.
Pluto (14th magnitude, in northwestern Sagittarius) is at its highest in the south around 11 p.m. See the finder chart in the June Sky & Telescope, page 53.
All descriptions that relate to your horizon or zenith — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.
"The universe is full of magical things patiently waiting for our wits to grow sharper."
— Eden Phillpotts, "A Shadow Passes," 1918
To be sure to get the current Sky at a Glance, bookmark this URL:
If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of the URL to any other character and try again.