The Observing LogStar charts · backyard targets

THE OBSERVING LOG · BACKYARD TARGETS

Every target on the same chart, filed the same way.

Each entry is one card: the kind of object it is, how bright it is, the season it sits well for evening viewing, the least equipment that shows it, the constellation to start from, and how hard it is to actually see. Compare a planet, a galaxy, and a double star without trusting a catalog to do the reading for you.

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8 targets Planets 8 targets Deep Sky 7 targets Lunar 7 targets Double Stars

Planets

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Planets Why Jupiter's Great Red Spot Is the Easiest Planet Feature to Track TypePlanet (gas giant) — a surface feature on Jupiter, the Great Red Spot, a long-lived anticyclonic storm MagJupiter itself ranges roughly from about -2.5 to -1.5 in apparent magnitude, bright enough to be seen with the unaided eye; the Great Red Spot is a low-contrast detail within the planet's disk and needs optical aid to resolve, so it is effectively a small-telescope target ScopeA small telescope is the least equipment that shows the Great Red Spot usefully; a modest aperture with moderate magnification reveals it as a pale oval, while larger apertures and steady air make it easier Jupiter is one of the most rewarding objects for a backyard observer, and the Great Red Spot is the single feature most people want to see. Planets Reading Saturn's Rings: What a Small Telescope Can Actually Show TypePlanet (Saturn) MagTypically around magnitude 0.5 to 1.0, easily visible to the naked eye; its rings require a telescope. ScopeA small telescope (60 mm to 150 mm aperture) is needed to see the rings; larger apertures reveal more detail. Saturn is the crown jewel of the solar system for many amateur astronomers. Planets Mars Opposition Years and Why the Planet Looks Different Each Time TypePlanet (Mars) MagRanges from about magnitude -2.9 at the brightest oppositions down to roughly magnitude +1.8 near solar conjunction; naked-eye whenever it is above the horizon, though small telescopic detail needs a modest instrument ScopeUnaided eye to find and track it; a small telescope is the least gear that shows the polar cap and dark surface markings under steady seeing Mars is the only bright planet whose appearance changes dramatically from one opposition to the next. Planets Spotting Mercury and Venus in Twilight Without Losing Them to the Sun TypePlanet (the two inferior planets, Mercury and Venus) MagVenus ranges roughly magnitude -3 to -5 and is easily naked-eye; Mercury ranges roughly magnitude -2 to +2 and is naked-eye when well placed but often lost in bright twilight ScopeUnaided eye to locate and follow; binoculars or a small telescope to see phases and, for Venus, a featureless disk Mercury and Venus are the two planets that orbit closer to the Sun than Earth does, which is exactly why they are so often described as twilight objects. Planets The Galilean Moons: Watching Jupiter's Four Bright Dots Move Nightly TypeMoons of Jupiter (the four Galilean satellites: Io, Europa, Ganymede, and Callisto) MagThe moons themselves range roughly from magnitude 5 to 6, bright enough for binoculars and often visible in a steady small telescope; Jupiter itself is far brighter, roughly magnitude -2 to -3 depending on the year, and is plainly naked-eye. ScopeBinoculars held steadily or braced will show the moons as tiny points near Jupiter; a small telescope at moderate magnification gives the clearest view of their changing positions. Jupiter is the largest planet in the solar system and one of the most rewarding targets for a backyard observer. Planets Uranus and Neptune: Finding the Planets That Look Like Stars TypePlanet (ice giants Uranus and Neptune) MagUranus about magnitude 5.7–6.0; Neptune about 7.8–8.0. Uranus is marginally naked-eye under very dark skies but usually binocular; Neptune requires binoculars or a small telescope. ScopeUranus: binoculars (7x50 or larger) or a small telescope; Neptune: at least 50mm binoculars, preferably a small telescope at 100x or more. Uranus and Neptune are the two outermost major planets in our solar system, often called ice giants because of their deep atmospheres rich in water, ammonia, and methane. Planets Planet Rotation and the Window When Each One Is Best Placed TypePlanet (Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune) MagMercury -2 to +5, Venus -5 to -3, Mars -3 to +2, Jupiter -3 to -1, Saturn -1 to +1, Uranus +5 to +6, Neptune +7 to +8; Mercury, Venus, Mars, Jupiter, and Saturn are naked-eye, Uranus is binocular, Neptune is telescope-only ScopeUnaided eye for Mercury, Venus, Mars, Jupiter, Saturn; binoculars for Uranus; small telescope for Neptune Planets are the wanderers of the night sky, and each one has a window when it is best placed for evening observing. Planets Why Atmospheric Seeing Ruins a Planet Just When You Want Detail TypePlanet (any of the bright planets visible in amateur telescopes) MagVaries by planet; typically brighter than magnitude 2 and often much brighter, making most planets easily naked-eye objects ScopeUnaided eye to locate; a small telescope (60–100 mm) is enough to show a planetary disk and some detail, though larger apertures help when seeing is steady Atmospheric seeing is the reason a planet that looked crisp in a photograph can turn into a boiling, wobbly blob at the eyepiece.

Deep Sky

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Deep Sky Eyes Versus Aperture: What Deep Sky Objects Actually Look Like TypeDeep sky objects in general, including nebulae, star clusters, and galaxies MagVaries widely; some clusters are naked-eye (e.g., magnitude 3-4), many nebulae and galaxies are binocular or telescope-only (magnitude 6-10+) ScopeUnaided eye for brightest clusters; binoculars reveal many; small telescope (60-100mm) shows structure in brighter objects When you look up at a dark sky, your eyes can pick out a surprising amount: the misty glow of the Milky Way, the tiny dipper shape of the Pleiades, and perhaps a faint smudge that turns out to be a galaxy millions of light-years away. Deep Sky Surface Brightness, Not Magnitude, Decides Whether You Can See a Galaxy TypeGalaxy (the article uses galaxies generally as the worked example, with the Andromeda Galaxy and the Triangulum Galaxy as familiar illustrations) MagIntegrated magnitudes of galaxies typically run from about 3.4 (Andromeda Galaxy, faintly naked-eye from a dark site) through 5.7 (Triangulum Galaxy, binocular) down to 9, 10, and fainter for most catalog galaxies, which are telescope-only; the key point is that integrated magnitude is spread over the whole object, so surface brightness is usually several magnitudes per square arcminute fainter ScopeBinoculars show the brightest galaxies as small smudges; a small telescope of about 80 to 150 mm aperture reveals the brighter galaxies and their cores, while larger apertures are needed for faint, low-surface-brightness objects Almost every galaxy in a catalog is listed with a single magnitude number, and that number is the source of more disappointment at the eyepiece than any other figure in amateur astronomy. Deep Sky Finding the Andromeda Galaxy by Star Hopping from Cassiopeia TypeGalaxy (spiral, the Andromeda Galaxy, M31) MagAbout magnitude 3.4; visible to the unaided eye under dark skies, and an easy binocular target even from suburban locations. ScopeUnaided eye from a dark site; binoculars or a small telescope reveal more detail. The Andromeda Galaxy is the nearest large spiral galaxy to our own Milky Way and the most distant object readily visible to the unaided eye. Deep Sky Why Globular Clusters Survive Light Pollution Better Than Nebulae TypeGlobular cluster (with comparison to nebula) MagTypically 5–9; bright ones naked-eye under dark skies, most binocular or small-telescope objects ScopeBinoculars or a small telescope (60–100 mm) for most; larger aperture improves resolution Globular clusters are dense, spherical swarms of ancient stars that orbit the outskirts of galaxies. Deep Sky Star Hopping to the Orion Nebula Without a Computerized Mount TypeNebula (emission nebula with an embedded young star cluster) MagAbout magnitude 4 overall, so it is faintly visible to the unaided eye under dark skies and easy in binoculars or any small telescope ScopeUnaided eye from a dark site, binoculars for a clear glow, and a small telescope for structure and the Trapezium stars The Orion Nebula is the brightest diffuse nebula in the sky and one of the few deep-sky objects that rewards a first look through almost any instrument. Deep Sky Dark Adaptation and the Twenty Minutes That Change What You See TypeNot a single object; the article covers the physiological process of dark adaptation as it applies to observing any deep-sky object (nebula, cluster, galaxy, double star, and so on) MagNot applicable to a process; dark adaptation improves the limiting magnitude of the observer's eye, often by several magnitudes, turning a naked-eye limit of about 4 to 5 in suburban skies into a limit that can reach 6 or fainter under dark skies ScopeUnaided eye for the process itself; binoculars or a small telescope to apply it to deep-sky targets Dark adaptation is the slow chemical and neural change that lets your eyes see faint things at night. Deep Sky Open Clusters as a Beginner's First Deep Sky Targets TypeOpen cluster (a loose group of stars born from the same cloud, still traveling together) MagMost beginner-friendly open clusters shine between magnitude 3 and 7; the brightest are naked-eye under dark skies, while fainter ones need binoculars or a small telescope. ScopeUnaided eye for the brightest, but binoculars or a small telescope reveal dozens of stars in most clusters. Open clusters are the friendly front door to deep-sky observing. Deep Sky The Virgo Cluster and Why Galaxy Hopping Feels Different TypeGalaxy cluster (rich cluster of galaxies) MagBrightest members around magnitude 8–10; most galaxies magnitude 10–13; telescope-only, though a few can be glimpsed with large binoculars under very dark skies ScopeSmall telescope (at least 80–100 mm aperture) to show the brightest galaxies; larger aperture (150 mm or more) needed to reveal many cluster members The Virgo Cluster is the nearest large galaxy cluster, a sprawling collection of hundreds of galaxies spread across the constellations Virgo and Coma Berenices.

Lunar

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Lunar The Terminator Line: Why the Moon Looks Best Away from Full TypeMoon (natural satellite) MagVaries with phase; full Moon about -12.7, quarter about -10, crescent about -6; easily naked-eye, and the brightest object in the night sky after the Sun ScopeUnaided eye shows the phase and major dark plains; binoculars reveal large craters and mountain ranges; a small telescope at moderate to high power shows the terminator, crater walls, central peaks, and rilles The Moon is the most rewarding object for a beginning observer, but many people look at it only when it is full. Lunar Reading a Lunar Map: Craters, Maria, and the Rays from Tycho TypeMoon (lunar surface features: craters, maria, ray systems) MagThe Moon is far brighter than any star, with a typical full-phase apparent magnitude around -12.7; it is easily naked-eye, and its surface details are best seen with binoculars or a small telescope. ScopeUnaided eye shows the maria and bright ray systems; binoculars reveal larger craters and mare boundaries; a small telescope (60–90 mm) shows hundreds of craters and finer ray details. The Moon is the most rewarding first target for any backyard observer, and a lunar map turns it from a bright disk into a readable landscape. Lunar Earthshine and the Faint Side of a Thin Crescent Moon TypeMoon (specifically the thin crescent phase, with earthshine on the dark side) MagThe crescent itself is very bright, roughly magnitude -4 to -10 depending on phase; earthshine is much fainter, typically around magnitude +2 to +4 per unit area, but visible to the naked eye and in binoculars. ScopeUnaided eye shows the crescent and earthshine; binoculars or a small telescope enhance the view of earthshine and lunar detail. Earthshine is the faint illumination of the Moon's dark side, caused by sunlight reflected from Earth back onto the lunar surface. Lunar Lunar Eclipses: What to Watch Before and After Totality TypeMoon (lunar eclipse event) MagThe Moon is about magnitude -12.7 at full, easily naked-eye; during totality it dims to roughly magnitude -3 to +2 depending on atmospheric conditions, still naked-eye but binoculars or a small telescope improve detail. ScopeUnaided eye for the overall event; binoculars or a small telescope reveal crater detail, the umbra's edge, and color changes during partial and total phases. A lunar eclipse happens when the Moon passes into Earth's shadow. Lunar Why the Moon Washes Out the Sky and When to Plan Around It TypeMoon MagVaries with phase; full Moon about magnitude -12.7, easily naked-eye, and visible in daylight ScopeUnaided eye for phase and earthshine; binoculars or a small telescope for craters and terminator detail The Moon is the brightest object in the night sky, and its light is the single biggest reason many deep-sky targets seem to vanish. Lunar Lunar Libration and the Edge Features You Usually Never See TypeMoon (Earth's natural satellite), specifically the lunar limb and libration zones MagThe Moon is far brighter than any star, with a typical full Moon magnitude around -12.7; easily naked-eye, and libration features are visible in binoculars or a small telescope. ScopeBinoculars or a small telescope (60–90 mm aperture) will show the major limb features and libration effects; a larger telescope reveals finer detail. The Moon is tidally locked to Earth, meaning it keeps the same face turned toward us at all times. Lunar Observing the Moon at High Magnification Without a Steady Mount TypeMoon (Earth's natural satellite) MagVaries from about -12.7 at full to about -2.5 at crescent; always naked-eye and overwhelmingly bright ScopeUnaided eye shows the Moon and its phases; binoculars reveal craters and maria; a small telescope at high magnification shows fine detail along the terminator The Moon is the most rewarding target for any backyard observer, and it is also the most forgiving.

Double Stars

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Double Stars Splitting Albireo and Why Color Contrast Makes a Double Memorable TypeDouble star (a colorful contrasting pair) MagAbout 3rd magnitude for the brighter component and about 5th magnitude for the fainter one, so the pair is easily seen with the unaided eye under decent skies and splits cleanly in binoculars or a small telescope ScopeBinoculars show the pair as two points of light; a small telescope at moderate magnification reveals the color contrast best Albireo is the star that marks the head of Cygnus, the Swan, and it is one of the most beloved double stars in the entire sky. Double Stars The Dawes Limit and the Smallest Gap Your Telescope Can Split TypeDouble star (any close pair used to test resolving power) MagVaries by pair; many test pairs are 4th to 7th magnitude, visible in binoculars or small telescopes, while closer pairs may be telescope only ScopeSmall telescope (60–100 mm) for wide pairs; larger aperture for separations near the Dawes limit The Dawes limit is a practical rule for the smallest angular gap a telescope can split into two stars. Double Stars Mizar and Alcor: Testing Your Eyes on a Famous Naked Eye Pair TypeDouble star (multiple star system) MagMizar about magnitude 2.2; Alcor about magnitude 4.0; both naked-eye ScopeUnaided eye for the pair; binoculars or small telescope to see Mizar's closer companion Mizar and Alcor form one of the most celebrated naked-eye pairs in the northern sky. Double Stars Why Close Doubles Need Steady Air More Than a Bigger Lens TypeDouble star MagTypically between 4th and 8th magnitude; most close pairs are telescopic, though wide pairs may be binocular or naked-eye ScopeSmall telescope (60–100 mm) for close pairs; binoculars for wide pairs Close double stars are pairs of stars that appear very near each other in the sky. Double Stars Color in Double Stars: Optical Illusion or Real Difference TypeDouble star (pairs of stars that appear close together in the sky, whether physically bound or merely aligned along the same line of sight) MagIndividual components of well-known pairs commonly range from about first to ninth magnitude; bright pairs are naked-eye or binocular objects, while tighter or fainter pairs need a small telescope ScopeUnaided eye for wide bright pairs, binoculars for most showpiece pairs, and a small telescope at moderate to high magnification for tight pairs and faint companions Double stars are among the most rewarding targets for a backyard observer because they ask for nothing more than a clear night and a little patience. Double Stars Using Double Stars to Check a Telescope's Collimation and Focus TypeDouble star (also used as a collimation and focus test target) MagVaries by chosen pair; typical test doubles range from about 2nd to 6th magnitude and are visible in a small telescope or binoculars, with some naked-eye examples ScopeA small telescope at moderate to high magnification; binoculars can show wide pairs but are less useful for fine collimation checks Double stars are among the most useful targets for checking a telescope's optical alignment and focus. Double Stars Star Hopping to Mizar, Albireo, and Other Showcase Doubles TypeDouble star (multiple showcase pairs, including true binaries and optical pairs) MagMizar about magnitude 2.2 with companion about 4.0; Albireo about 3.1 with companion about 5.1; both are naked-eye or binocular targets, with the companion easiest in a small telescope ScopeUnaided eye for the primary stars; binoculars for wide pairs; a small telescope for close or faint companions Double stars are among the most rewarding targets for a backyard observer because they ask for attention rather than aperture.